JPWO2009107375A1 - Exhaust device for internal combustion engine - Google Patents

Abstract

In the back pressure regulator (15) of the exhaust device, three exhaust pipe units (20, 40, 60) are arranged in a line. In each exhaust pipe unit (20, ...), the base end of the inner exhaust pipe (22, ...) is inserted into the outer exhaust pipe (21, ...), and a cylindrical gap (23, 43, 63) is formed between them. It is formed. In addition, communication openings (24, 44, 64) that are through holes are formed in the outer exhaust pipe (21,...). The circular pipe part (31, 51, 71) of the spacer member (30, 50, 70) has an inner diameter equal to the outer diameter of the inner exhaust pipe (22, ...), and the outer diameter is the outer exhaust pipe (21, ...). ) Is equal to the inner diameter. When this circular pipe part (31, ...) is inserted between the outer exhaust pipe (21, ...) and the inner exhaust pipe (22, ...), the outer exhaust pipe (21, ...) and the inner exhaust pipe (22, ...) And the thickness of the cylindrical gap (23, 43, 63) becomes uniform over the entire circumference of the outer exhaust pipe (21,...).

Description

  The present invention relates to an exhaust device for exhausting exhaust gas of an internal combustion engine into the atmosphere.

  Conventionally, an exhaust device such as a muffler provided in an exhaust pipe connected to an internal combustion engine is known. Some exhaust devices of this type are configured so that the flow resistance of exhaust gas flowing therethrough can be changed.

  For example, Patent Document 1 discloses an exhaust muffler provided with a control valve composed of a so-called butterfly valve. In this exhaust muffler, a control valve is provided in a tail pipe for discharging exhaust gas from the muffler main body into the atmosphere. In this exhaust muffler, the flow passage cross-sectional area of the tail pipe is changed by operating the control valve so that the flow resistance of the exhaust gas in the tail pipe becomes an appropriate value according to the flow rate of the exhaust gas. .

  Patent Document 2 discloses an exhaust device that can change the flow resistance of exhaust gas without using a mechanical valve such as a butterfly valve. The exhaust device includes a cylindrical outer cylinder whose both ends are closed. In the outer cylinder, one exhaust gas introduction pipe is inserted from one end side of the outer cylinder, and two exhaust gas outlet pipes are inserted from the other end side of the outer cylinder. The exhaust gas inlet pipe and the first exhaust gas outlet pipe are arranged coaxially. The first exhaust gas outlet pipe has a smaller diameter than the exhaust gas introduction pipe, and the base end thereof is inserted into the distal end of the exhaust gas introduction pipe. A gap is formed between the inner peripheral surface of the exhaust gas introduction pipe and the outer peripheral surface of the first exhaust gas outlet pipe. On the other hand, the second exhaust gas lead-out pipe is provided substantially parallel to the first exhaust gas lead-out pipe and communicates the inside and outside of the outer cylinder.

  The operation of the exhaust device disclosed in Patent Document 2 will be described.

  First, when the rotational speed of the internal combustion engine is low and the flow rate of the exhaust gas is small, almost all of the exhaust gas flowing into the exhaust gas introduction pipe flows into the first exhaust gas lead-out pipe and the first exhaust gas lead-out. It is discharged into the atmosphere through a tube. That is, in this case, the cross-sectional area of the passage through which the exhaust gas is discharged from the exhaust device into the atmosphere is substantially equal to the cross-sectional area of the first exhaust gas outlet pipe.

  Next, when the rotational speed of the internal combustion engine is high and the flow rate of the exhaust gas is large, only a part of the exhaust gas flowing into the exhaust gas introduction pipe flows into the first exhaust gas outlet pipe, and the rest is the exhaust gas. It flows into the inner space of the outer cylinder through the gap between the introduction pipe and the first exhaust gas outlet pipe. The exhaust gas that has flowed into the first exhaust gas outlet pipe passes through the first exhaust gas outlet pipe and is discharged into the atmosphere as it is. On the other hand, the exhaust gas flowing into the internal space of the outer cylinder is discharged into the atmosphere through the second exhaust gas outlet pipe. That is, in this case, the cross-sectional area of the passage through which the exhaust gas is discharged from the exhaust device into the atmosphere is the sum of the cross-sectional area of the first exhaust gas outlet pipe and the cross-sectional area of the second exhaust gas outlet pipe. And substantially equal.

Thus, in the exhaust device disclosed in Patent Document 2, the cross-sectional area of the passage through which exhaust gas is discharged from the exhaust device into the atmosphere automatically changes according to the flow rate of the exhaust gas.
Japanese Patent Laid-Open No. 10-252443 Japanese Patent Laid-Open No. 2003-232212

  As described above, in the exhaust device of Patent Document 2, the exhaust gas is discharged from the exhaust device into the atmosphere depending on whether or not the exhaust gas passes through the gap between the exhaust gas introduction pipe and the first exhaust gas outlet pipe. The cross-sectional area of the passage that passes through is changed. Therefore, in this exhaust system, it is necessary to accurately manage the interval between the exhaust gas introduction pipe and the first exhaust gas outlet pipe in order to reduce the performance difference between products.

  However, in the exhaust device disclosed in Patent Document 2, the exhaust gas introduction pipe is fixed to one end of the outer cylinder, while the first exhaust gas outlet pipe is fixed to the other end of the outer cylinder. Therefore, in this exhaust device, the positional relationship between the distal end of the exhaust gas introduction pipe joined to one end of the outer cylinder and the proximal end of the first exhaust gas outlet pipe joined to the other end of the outer cylinder is determined. There is a problem that it is difficult to set accurately, and it is difficult to suppress variation in performance of each product.

  The present invention has been made in view of the above point, and an object of the present invention is to reduce the performance difference between products for an exhaust device capable of adjusting the flow resistance of exhaust gas without using mechanical means such as a valve. It is to improve the reliability.

  The first invention relates to an exhaust device for an internal combustion engine. An outer exhaust pipe (21, 41, 61) that is formed in a circular tube shape into which the exhaust gas of the internal combustion engine flows from the base end side, and is formed in a circular tube having an outer diameter smaller than the inner diameter of the outer exhaust pipe. The inner exhaust pipe (22, 42, 62) inserted into the tip of the outer exhaust pipe (21, 41, 61), the inner peripheral surface of the outer exhaust pipe (21, 41, 61) and the inner exhaust pipe ( 22, 42, 62) are provided between the outer exhaust pipe (21, 41, 61) and the inner exhaust pipe (22, 42, 62) in order to make the interval between the outer peripheral surfaces constant over the entire circumference. Spacing member (30, 50, 70), cylinder formed between the inner peripheral surface of the outer exhaust pipe (21, 41, 61) and the outer peripheral surface of the inner exhaust pipe (22, 42, 62) A communication opening (24, 44, 64) is provided for communicating the gap (23, 43, 63) with the outside of the outer exhaust pipe (21, 41, 61).

  In the first invention, the base end of the inner exhaust pipe (22, 42, 62) is inserted into the distal end of the outer exhaust pipe (21, 41, 61), and the inner peripheral surface of the outer exhaust pipe (21, 41, 61). A cylindrical gap (23, 43, 63) is formed between the outer peripheral surface of the inner exhaust pipe (22, 42, 62). The cylindrical gap (23, 43, 63) communicates with the space outside the outer exhaust pipe (21, 41, 61) through the communication opening (24, 44, 64). A spacing member (30, 50, 70) is provided between the outer exhaust pipe (21, 41, 61) and the inner exhaust pipe (22, 42, 62). 61) and the inner exhaust pipe (22, 42, 62) are kept constant by the spacing member (30, 50, 70). For this reason, the width (that is, the thickness in the radial direction) of the cylindrical gap (23, 43, 63) is the entire circumference of the outer exhaust pipe (21, 41, 61) and the inner exhaust pipe (22, 42, 62). Over the entire range.

  In the exhaust device (10) according to the first aspect of the present invention, the exhaust gas flows out from the tip of the inner exhaust pipe (22, 42, 62) and one of the communication openings (24, 44, 64), and the inner exhaust pipe ( The flow rate of exhaust gas flowing into the base end of the outer exhaust pipe (21, 41, 61) when exhaust gas flows out from both the front end of the communication opening (24, 44, 64) and the communication opening (24, 44, 64) It switches according to. That is, in this exhaust device (10), when the flow rate of the exhaust gas is relatively small, the exhaust gas flows from the tip of the inner exhaust pipe (22, 42, 62) and one of the communication openings (24, 44, 64). On the other hand, when the flow rate of the exhaust gas is relatively high, the exhaust gas flows out from both the front end of the inner exhaust pipe (22, 42, 62) and the communication opening (24, 44, 64).

  In a second aspect based on the first aspect, the spacing member (30, 50, 70) is inserted into the cylindrical gap (23, 43, 63) and the outer exhaust pipe (21, 41). , 61) and the outer peripheral surface of the inner exhaust pipe (22, 42, 62).

  In the second invention, the spacing member (30, 50, 70) inserted between the outer exhaust pipe (21, 41, 61) and the inner exhaust pipe (22, 42, 62) is provided with the outer exhaust pipe ( 21, 41, 61) and the outer peripheral surface of the inner exhaust pipe (22, 42, 62). That is, in the exhaust device (10) of the present invention, the distance between the outer exhaust pipe (21, 41, 61) and the inner exhaust pipe (22, 42, 62) is the interval holding member (30 , 50, 70).

  In a third aspect based on the second aspect, the spacing member (30, 50, 70) is arranged so that the cylindrical gap (23, 43) extends from the distal end side of the outer exhaust pipe (21, 41, 61). , 63).

  In the third invention, the spacing member (30, 50, 70) is inserted into the outer exhaust pipe (21, 41, 61) from the front end side thereof, and is connected to the outer exhaust pipe (21, 41, 61). It contacts both the inner exhaust pipes (22, 42, 62). That is, the outer exhaust pipe (21, 41, 61) is connected to the cylindrical gap (23, 43, 63) formed between the outer exhaust pipe (21, 41, 61) and the inner exhaust pipe (22, 42, 62). 61) The spacing member (30, 50, 70) is inserted from the front end side.

  According to a fourth invention, in the third invention, the spacing member (30, 50, 70) has an outer diameter equal to an inner diameter of the outer exhaust pipe (21, 41, 61) and an inner diameter of the inner member. While having a circular pipe part (31, 51, 71) formed in a circular tube having the same outer diameter as the exhaust pipe (22, 42, 62) and inserted into the cylindrical gap (23, 43, 63), In the outer exhaust pipe (21, 41, 61), the cylindrical gap (23, 43, 23) is overlapped with the inner exhaust pipe (22, 42, 62) inserted into the outer exhaust pipe (21, 41, 61). , 63) is formed, and the through hole constitutes the communication opening (24, 44, 64).

  In 4th invention, a circular pipe part (31,51,71) is provided in the space | interval holding member (30,50,70). This circular pipe part (31,51,71) is located between the outer exhaust pipe (21,41,61) and the inner exhaust pipe (22,42,62) at the tip side of the outer exhaust pipe (21,41,61). Is inserted from. The circular pipe part (31,51,71) has its outer peripheral surface in contact with the inner peripheral surface of the outer exhaust pipe (21,41,61), and its inner peripheral surface is the outer periphery of the inner exhaust pipe (22,42,62) Touch the surface. For this reason, the cylindrical gaps (23, 43, 63) formed between the outer exhaust pipe (21, 41, 61) and the inner exhaust pipe (22, 42, 62) are separated from the outer exhaust pipe (21, 41, 61). The part near the tip of 61) is blocked by the circular pipe part (31, 51, 71).

  In the outer exhaust pipe of the fourth invention, a through hole is formed in a portion overlapping with the inner exhaust pipe (22, 42, 62) inserted into the outer exhaust pipe (21, 41, 61). The cylindrical gap (23, 43, 63) closed by the circular pipe portion communicates with the outside of the outer exhaust pipe (21, 41, 61) through this through hole. That is, in the exhaust device (10) of the present invention, the through holes formed in the outer exhaust pipe (21, 41, 61) serve as communication openings (24, 44, 64).

  According to a fifth invention, in the fourth invention, the spacing member (30, 50, 70) is formed in an annular shape having an outer diameter larger than an inner diameter of the outer exhaust pipe (21, 41, 61). The annular projecting portion (32, 52, 72) is formed continuously at the tip of the circular tube portion (31, 51, 71), and the annular projecting portion (32, 52, 72) is It is in contact with the front end surface of the outer exhaust pipe (21, 41, 61).

  In the fifth invention, the spacing member (30, 50, 70) is provided with the circular pipe portion (31, 51, 71) and the annular protrusion (32, 52, 72). The annular protrusion (32, 52, 72) is formed continuously at the tip of the circular pipe part (31, 51, 71), and its outer diameter is the inner diameter of the outer exhaust pipe (21, 41, 61). Is bigger than. The state where the circular pipe part (31, 51, 71) of the spacing member (30, 50, 70) is inserted between the outer exhaust pipe (21, 41, 61) and the inner exhaust pipe (22, 42, 62) , The annular protrusions (32, 52, 72) of the spacing member (30, 50, 70) are exposed to the outside of the outer exhaust pipe (21, 41, 61) and the outer exhaust pipe (21, 41, 61). 61) Abut on the tip surface.

  In a sixth aspect based on the third aspect, the spacing member (30, 50, 70) has an outer diameter equal to an inner diameter of the outer exhaust pipe (21, 41, 61) and an inner diameter equal to the inner diameter. While the exhaust pipe (22, 42, 62) is formed in a circular tube shape equal to the outer diameter of the exhaust pipe (22, 42, 62), the spacing member (30, 50, 70) is provided with the spacing member (30, 50, 70). A notch (33, 53, 73) extending from the base end in the axial direction of the spacing member (30, 50, 70) is formed, and the spacing member (30, 50, 70) is From the base end side of the spacing member (30, 50, 70), the cylindrical shape so that only a part of the notch (33, 53, 73) is covered by the outer exhaust pipe (21, 41, 61). A portion of the notch (33, 53, 73) that is inserted into the gap (23, 43, 63) and not covered by the outer exhaust pipe (21, 41, 61) is the communication opening (24 , 44, 64).

  In the sixth invention, the notches (33, 53, 73) are formed in the spacing member (30, 50, 70) formed in a circular tube shape. Notches (33, 53, 73) are formed in the spacing member (30, 50, 70). This notch (33, 53, 73) is a predetermined part in the circumferential direction of the spacing member (30, 50, 70) from the base end of the spacing member (30, 50, 70) in the axial direction. It is formed by excising over the length. The spacing member (30, 50, 70) has an outer diameter equal to the inner diameter of the outer exhaust pipe (21, 41, 61), and its inner diameter is equal to the outer diameter of the inner exhaust pipe (22, 42, 62). . For this reason, the non-removed portion (35, 55, 75) of the base end side portion of the spacing member (30, 50, 70) that remains without being cut has a radius of curvature on the outer side of the outer exhaust. It is equal to half the inner diameter of the pipe (21, 41, 61), and the radius of curvature of its inner surface is equal to half of the outer diameter of the inner exhaust pipe (22, 42, 62). Between the outer exhaust pipe (21,41,61) and the inner exhaust pipe (22,42,62), the non-cut portion (35,55,75) of the spacing member (30,50,70) is outside. It is inserted from the tip side of the exhaust pipe (21, 41, 61). The spacing member (30, 50, 70) is configured such that the outer surface of the non-cut portion (35, 55, 75) is in contact with the inner peripheral surface of the outer exhaust pipe (21, 41, 61), and the non-cut portion (35, 55, 75) 55, 75) is in contact with the outer peripheral surface of the inner exhaust pipe (22, 42, 62).

  In the sixth invention, the notches (33, 53, 73) formed in the spacing member (30, 50, 70) are partially covered by the outer exhaust pipe (21, 41, 61), and the rest Is exposed outside the outer exhaust pipe (21, 41, 61). For this reason, the cylindrical gaps (23, 43, 63) formed between the outer exhaust pipe (21, 41, 61) and the inner exhaust pipe (22, 42, 62) are separated from the gap retaining member (30, 50). , 70) communicates with the outside of the outer exhaust pipe (21, 41, 61) through notches (33, 53, 73) formed in the outer exhaust pipe (21, 41, 61). In other words, in the exhaust device (10) of the present invention, the outer exhaust pipe (21, 41, 61) is covered by the notches (33, 53, 73) formed in the spacing member (30, 50, 70). The part which is not broken becomes a communication opening (24, 44, 64).

  According to a seventh invention, in any one of the first to sixth inventions, the inner surface faces the outer peripheral surface of the outer exhaust pipe (21, 41, 61) with a space therebetween. A tubular member (18) is provided.

  In the seventh invention, the exhaust device (10) is provided with the tubular member (18). The inner surface of the tubular member (18) faces the outer peripheral surface of the outer exhaust pipe (21, 41, 61). Further, the inner side surface of the tubular member (18) and the outer peripheral surface of the outer exhaust pipe (21, 41, 61) are separated from each other, and a space is formed between them. That is, in the exhaust device (10) of the present invention, the outer exhaust pipe (21, 41, 61) is surrounded by the tubular member (18). And the exhaust gas which flowed into the cylindrical clearances (23, 43, 63) formed between the outer exhaust pipe (21, 41, 61) and the inner exhaust pipe (22, 42, 62) is the tubular member (18 ) Flows out through the communication opening (24, 44, 64).

  In an eighth aspect based on the seventh aspect, a portion of the outer exhaust pipe (21, 41) closer to the base end of the outer exhaust pipe (21, 41) than the communication opening (24, 44). And the tubular member (18) are provided with a closing member (218).

  In the eighth invention, the closing member (218) is provided in the exhaust device (10) together with the tubular member (18). The blocking member (218) includes a portion of the outer exhaust pipe (21, 41) closer to the proximal end of the outer exhaust pipe (21, 41) than the communication opening (24, 44) and the tubular member (18). It is closing the space. That is, the space inside the tubular member (18) is blocked by the closing member (218) at a position closer to the base end of the outer exhaust pipe (21, 41) than the communication opening (24, 44). . The end of the tubular member (18) opposite to the closing member (218) is an open end.

  According to a ninth invention, in any one of the first to sixth inventions, one each of the outer exhaust pipe (21, 41, 61) and the inner exhaust pipe (22, 42, 62). And a plurality of exhaust pipe units (20, 40, 60) each having the communication opening (24, 44, 64). The exhaust pipe units (20, 40, 60) are arranged in a row so that the outer exhaust pipes (21, 41, 61) and the inner exhaust pipes (22, 42, 62) are coaxially positioned. Is.

  In the ninth invention, in the two adjacent exhaust pipe units (20, 40), the inner exhaust pipe (42) constituting the downstream exhaust pipe unit (40) has an inner diameter of the upstream exhaust pipe unit. It is smaller than the inner diameter of the inner exhaust pipe (22) of (20), and the inner diameter of the outer exhaust pipe (41) constituting the downstream exhaust pipe unit (40) is the inner side of the upstream exhaust pipe unit (20). The outer diameter of the outer exhaust pipe (22) is the same as the outer diameter of the exhaust pipe (22), and the tip of the inner exhaust pipe (22) constituting the upstream exhaust pipe unit (20) 41) between the proximal end of the inner exhaust pipe (42) of the downstream exhaust pipe unit (40) and the distal end of the inner exhaust pipe (22) of the upstream exhaust pipe unit (20). A gap is formed.

  According to a tenth aspect of the present invention, in the fourth or sixth aspect of the present invention, one outer exhaust pipe (21, 41, 61), one inner exhaust pipe (22, 42, 62), and one for holding the gap. A plurality of exhaust pipe units each including a plurality of exhaust pipe units (20, 40, 60) each having the communication opening (24, 44, 64). (20, 40, 60) are arranged in a row so that the respective outer exhaust pipes (21, 41, 61) and inner exhaust pipes (22, 42, 62) are coaxially positioned.

  In the tenth invention, in the two adjacent exhaust pipe units (20, 40), the inner exhaust pipe (42) constituting the downstream exhaust pipe unit (40) has an inner diameter of the upstream exhaust pipe unit. (20) is smaller than the inner diameter of the inner exhaust pipe (22), and the inner diameter of the outer exhaust pipe (41) constituting the downstream exhaust pipe unit (40) is smaller than the upstream exhaust pipe unit (20). The inner exhaust which is smaller than the inner diameter of the outer exhaust pipe (21) and larger than the inner diameter of the inner exhaust pipe (22) of the upstream exhaust pipe unit (20) and constitutes the upstream exhaust pipe unit (20) The distal end of the pipe (22) is inserted into the proximal end of the outer exhaust pipe (41) constituting the downstream exhaust pipe unit (40), and the outer exhaust pipe (41) constituting the downstream exhaust pipe unit (40). ) And the inner exhaust pipe (42), the cylindrical gap (43) is the upstream exhaust pipe unit. And it communicates the inner space and the communication of the inner exhaust pipe (22) constituting a 20).

  In the tenth aspect of the invention, the two adjacent exhaust pipe units (20, 40) include an outer exhaust pipe (41) of the downstream exhaust pipe unit (40) and an upstream exhaust pipe unit (20). The spacing holding member (30) is integrally formed.

  In each of the ninth and tenth aspects, the exhaust device (10) is provided with a plurality of exhaust pipe units (20, 40, 60). Each exhaust pipe unit (20, 40, 60) has one outer exhaust pipe (21, 41, 61), inner exhaust pipe (22, 42, 62), and spacing member (30, 50, 70). And is composed of. Each exhaust pipe unit (20, 40, 60) is provided with a communication opening (24, 44, 64). The plurality of exhaust pipe units (20, 40, 60) are arranged in a row so that the respective outer exhaust pipes (21, 41, 61) and inner exhaust pipes (22, 42, 62) are coaxially positioned.

  In the ninth invention, in the two adjacent exhaust pipe units (20, 40), the inner diameter of the outer exhaust pipe (41) constituting the downstream exhaust pipe unit (40) is equal to the upstream exhaust pipe unit ( 20) is equal to the outer diameter of the inner exhaust pipe (22). In the upstream exhaust pipe unit (20), the outer diameter of the inner exhaust pipe (22) is smaller than the inner diameter of the outer exhaust pipe (21). Accordingly, the inner diameter of the outer exhaust pipe (41) constituting the downstream exhaust pipe unit (40) is smaller than the inner diameter of the outer exhaust pipe (21) constituting the upstream exhaust pipe unit (20). . That is, according to the present invention, the inner diameters of the outer exhaust pipe (41, 61) and the inner exhaust pipe (42, 62) are smaller in the exhaust pipe unit (40, 60) arranged on the downstream side of the exhaust gas flow. Yes.

  In the ninth aspect of the invention, the inner exhaust pipe (22) constituting the upstream exhaust pipe unit (20) is disposed at the proximal end of the outer exhaust pipe (41) constituting the downstream exhaust pipe unit (40). The tip of is inserted. Inside the outer exhaust pipe (41) constituting the downstream exhaust pipe unit (40), the tip of the inner exhaust pipe (22) constituting the upstream exhaust pipe unit (20) and the downstream exhaust pipe unit The base end of the inner exhaust pipe (42) constituting (40) faces each other, and a gap is formed between them.

  In the tenth invention, the inner diameters of the outer exhaust pipe (41, 61) and the inner exhaust pipe (42, 62) become smaller as the exhaust pipe unit (40, 60) arranged on the downstream side of the exhaust gas flow. Yes. In the present invention, in the two adjacent exhaust pipe units (20, 40), the inner diameter of the outer exhaust pipe (41) constituting the downstream exhaust pipe unit (40) is the upstream exhaust pipe unit (20). Is smaller than the inner diameter of the outer exhaust pipe (21), and larger than the inner diameter of the inner exhaust pipe (22) of the upstream exhaust pipe unit (20).

  In the tenth aspect of the invention, in the two adjacent exhaust pipe units (20, 40), the upstream exhaust pipe is disposed at the base end of the outer exhaust pipe (41) constituting the downstream exhaust pipe unit (40). The tip of the inner exhaust pipe (22) constituting the pipe unit (20) is inserted. In the downstream exhaust pipe unit (40), a cylindrical gap (43) is formed between the outer exhaust pipe (41) and the inner exhaust pipe (42). The cylindrical gap (43) formed in the downstream exhaust pipe unit (40) communicates with the space inside the inner exhaust pipe (22) constituting the upstream exhaust pipe unit (20). For this reason, the exhaust gas that has passed through the inner exhaust pipe (22) of the upstream exhaust pipe unit (20) can flow into the cylindrical gap (43) formed in the downstream exhaust pipe unit (40).

  Furthermore, in the tenth invention, the spacing member (30) of the upstream exhaust pipe unit (20) is formed integrally with the outer exhaust pipe (41) of the downstream exhaust pipe unit (40). . That is, in the two adjacent exhaust pipe units (20, 40), the interval holding member (30) of the upstream exhaust pipe unit (20) and the outer exhaust pipe of the downstream exhaust pipe unit (40) ( 41) is constituted by one member inseparable from each other.

  An eleventh aspect of the invention is the invention according to any one of the first to sixth aspects, wherein each of the outer exhaust pipe (21, 41, 61) and the inner exhaust pipe (22, 42, 62) is one each. And a plurality of exhaust pipe units (20, 40, 60) each having the communication opening (24, 44, 64). The exhaust pipe units (20, 40, 60) are arranged in a row so that the outer exhaust pipes (21, 41, 61) and the inner exhaust pipes (22, 42, 62) are coaxially positioned. On the other hand, a tubular member (18) is provided which is formed in a tubular shape and whose inner surface faces the outer peripheral surfaces of all the outer exhaust pipes (21, 41, 61) at an interval.

  In the eleventh invention, the exhaust device (10) is provided with a plurality of exhaust pipe units (20, 40, 60). Each exhaust pipe unit (20, 40, 60) has one outer exhaust pipe (21, 41, 61), inner exhaust pipe (22, 42, 62), and spacing member (30, 50, 70). And is composed of. Each exhaust pipe unit is provided with a communication opening (24, 44, 64). The plurality of exhaust pipe units (20, 40, 60) are arranged in a row so that the respective outer exhaust pipes (21, 41, 61) and inner exhaust pipes (22, 42, 62) are coaxially positioned.

  In the eleventh invention, the exhaust device (10) is provided with a tubular member (18). The inner surface of the tubular member (18) faces the outer peripheral surface of all the outer exhaust pipes (21, 41, 61). Further, the inner side surface of the tubular member (18) and the outer peripheral surface of each outer exhaust pipe (21, 41, 61) are separated from each other, and a space is formed between them. That is, in the exhaust device (10) of the present invention, the periphery of all the exhaust pipe units (20, 40, 60) is surrounded by the tubular member (18). In the exhaust pipe unit (20, 40, 60), a cylindrical gap (23, 43, 63) formed between the outer exhaust pipe (21, 41, 61) and the inner exhaust pipe (22, 42, 62). The exhaust gas that has flowed into () passes through the communication openings (24, 44, 64) and flows out into the space inside the tubular member (18).

  In the exhaust device (10) of the present invention, the exhaust gas flows out from one end of the front end of the inner exhaust pipe (22, 42, 62) and the communication opening (24, 44, 64), and the inner exhaust pipe (22, 42, 62) and the state where the exhaust gas flows out from both the communication opening (24, 44, 64) depends on the flow rate of the exhaust gas flowing into the base end of the outer exhaust pipe (21, 41, 61) To switch. Therefore, according to the present invention, the cross-sectional area of the passage through which the exhaust gas flows out from the exhaust device (10) can be adjusted without using mechanical means such as a valve. As a result, the flow resistance of the exhaust gas in the exhaust device (10) can be set to an appropriate value according to the flow rate of the exhaust gas, and the loss of the internal combustion engine accompanying the exhaust gas discharge can be reduced.

  Furthermore, in the exhaust device (10) of the present invention, the spacing member (30, 50, 70) provided between the outer exhaust pipe (21, 41, 61) and the inner exhaust pipe (22, 42, 62). Thus, the distance between the outer exhaust pipe (21, 41, 61) and the inner exhaust pipe (22, 42, 62) is kept constant over the entire circumference. For this reason, according to the present invention, the distance between the outer exhaust pipe (21, 41, 61) and the inner exhaust pipe (22, 42, 62) can be easily and reliably kept constant, and there is a difference in performance between products. The reliability of the exhaust device (10) can be improved by reducing the size of the exhaust device.

  In the second aspect of the invention, the spacing member (30, 50, 70) is inserted between the outer exhaust pipe (21, 41, 61) and the inner exhaust pipe (22, 42, 62), and the outer exhaust The distance between the pipe (21, 41, 61) and the inner exhaust pipe (22, 42, 62) is substantially equal to the thickness of the spacing member (30, 50, 70). For this reason, in the exhaust device (10) of the present invention, by managing the dimensional accuracy of the spacing member (30, 50, 70) so that the thickness thereof is constant, the outer exhaust pipe (21, 41, 61) and the thickness of the cylindrical gap (23, 43, 63) formed between the inner exhaust pipe (22, 42, 62) can be managed. Therefore, according to the present invention, the difference in the thickness of the cylindrical gap (23, 43, 63) for each product can be easily and reliably suppressed, and the performance difference for each product can be easily and reliably reduced. Can do.

  In the third aspect of the invention, the spacing member (30, 50, 70) is inserted into the outer exhaust pipe (21, 41, 61) from the tip side. That is, the outer exhaust pipe (21, 41, 61) is connected to the cylindrical gap (23, 43, 63) formed between the outer exhaust pipe (21, 41, 61) and the inner exhaust pipe (22, 42, 62). 61) The spacing member (30, 50, 70) is inserted from the front end side. Therefore, according to the present invention, the gap retaining member (30) is obtained without hindering the flow of the exhaust gas flowing from the proximal end side of the outer exhaust pipe (21, 41, 61) into the cylindrical gap (23, 43, 63). , 50, 70), the distance between the outer exhaust pipe (21, 41, 61) and the inner exhaust pipe (22, 42, 62) can be maintained.

  In the fourth invention, the circular pipe part (31, 51, 71) of the spacing member (30, 50, 70) includes the outer exhaust pipe (21, 41, 61) and the inner exhaust pipe (22, 42, 62). And since the circular pipe part (31,51,71) is formed in a circular tube shape, the outer peripheral surface of the circular pipe part (31,51,71) extends to the outer exhaust pipe (21,41,61) over the entire circumference. ) And the inner peripheral surface of the circular pipe portion (31, 51, 71) is in contact with the outer peripheral surface of the inner exhaust pipe (22, 42, 62) over the entire circumference. Therefore, according to the present invention, the distance between the outer exhaust pipe (21, 41, 61) and the inner exhaust pipe (22, 42, 62) can be reliably kept constant by the circular pipe portion (31, 51, 71). The thickness of the cylindrical gaps (23, 43, 63) can be easily and reliably kept constant.

  In the fifth invention, the spacing member (30, 50, 70) is provided with the circular pipe portion (31, 51, 71) and the annular protrusion (32, 52, 72). In the state where the circular pipe portion (31, 51, 71) is inserted between the outer exhaust pipe (21, 41, 61) and the inner exhaust pipe (22, 42, 62), the annular protrusion (32, 52 72) abuts against the front end surface of the outer exhaust pipe (21, 41, 61). That is, when assembling the exhaust device (10) of the present invention, the circular pipe portion (31, 51, 72) until the annular projection (32, 52, 72) hits the tip surface of the outer exhaust pipe (21, 41, 61). 71) is inserted into the cylindrical gap (23, 43, 63), the relative positional relationship between the outer exhaust pipe (21, 41, 61) and the spacing member (30, 50, 70) is uniquely determined. It will be. Therefore, according to the present invention, it is possible to easily and reliably position the spacing member (30, 50, 70) with respect to the outer exhaust pipe (21, 41, 61), and the exhaust device (10) Labor and time required for assembly can be reduced.

  In the sixth aspect of the invention, the spacing member (30, 50, 70) in which the notches (33, 53, 73) are formed has a part of the notches (33, 53, 73) in the outer exhaust pipe ( 21, 41, 61) is inserted between the outer exhaust pipe (21, 41, 61) and the inner exhaust pipe (22, 42, 62) from the base end side so as to be exposed from the inner exhaust pipe (22, 42, 62). Therefore, the cylindrical gaps (23, 43, 63) formed between the outer exhaust pipe (21, 41, 61) and the inner exhaust pipe (22, 42, 62) are separated from the gap retaining member (30, 50, It communicates with the outside of the outer exhaust pipe (21, 41, 61) via the notch (33, 53, 73) formed in 70). As described above, according to the present invention, the portion in which the notch (33, 53, 73) is formed in the spacing member (30, 50, 70) is inserted into the outer exhaust pipe (21, 41, 61). By doing so, the cylindrical gap (23, 43, 63) can be communicated with the outside of the outer exhaust pipe (21, 41, 61).

  By the way, in the exhaust device (10) of the present invention, to the cylindrical gap (23, 43, 63) formed between the outer exhaust pipe (21, 41, 61) and the inner exhaust pipe (22, 42, 62). The exhaust gas that has flowed in is blown out from the communication openings (24, 44, 64). For this reason, if there is an air flow in the vicinity of the communication opening (24, 44, 64), the flow of exhaust gas blown out from the communication opening (24, 44, 64) is obstructed by the air flow, and the exhaust device ( 10) Performance may be adversely affected. In particular, when the exhaust system (10) of the present invention is mounted on an automobile together with an internal combustion engine, air flows in the vicinity of the communication opening (24, 44, 64) as the automobile travels. There is a high possibility that it will cause the performance degradation of the exhaust system (10).

  On the other hand, in the exhaust device (10) of each of the seventh, eighth, and eleventh inventions, the outer exhaust pipe (21, 41, 61) is surrounded by the tubular member (18) for communication. Air flow is less likely to occur near the openings (24, 44, 64). Therefore, according to these inventions, the influence of the exhaust gas flow passing through the communication opening (24, 44, 64) from the air flow existing in the vicinity of the communication opening (24, 44, 64) is reduced. It is possible to suppress a decrease in performance of the exhaust device (10) due to the air flow in the vicinity of the communication opening (24, 44, 64).

  In particular, in the eighth aspect of the invention, the tubular member (18) is closed at its proximal end by the closing member (218), and only its distal end is an open end. Therefore, according to the present invention, the air flow in the vicinity of the communication opening (24, 44, 64) can be reliably suppressed, and the air flow in the vicinity of the communication opening (24, 44, 64) is caused. The performance deterioration of the exhaust device (10) to be performed can be further reduced.

  In the exhaust device (10) of the ninth, tenth and eleventh inventions, a plurality of exhaust pipe units (20, 40, 60) are connected in a row. Therefore, according to these inventions, the cross-sectional area of the passage through which the exhaust gas passes through the exhaust device (10) into the atmosphere can be changed in multiple stages.

  This point will be described by taking as an example a case where the exhaust device (10) is provided with three exhaust pipe units (20, 40, 60). In this case, in the exhaust device (10), the exhaust gas can flow out from the communication opening (24) of the exhaust pipe unit (20) provided in the uppermost stream and the exhaust pipe unit (40) provided in the middle. The communication opening (44), the communication opening (64) of the exhaust pipe unit (60) provided at the most downstream position, and the inner exhaust pipe (62) of the exhaust pipe unit (60) provided at the most downstream position. There are four points at the tip. In the exhaust device (10) in this case, when the flow rate of the exhaust gas is small, the exhaust gas flows out from only one of the four locations, and the location where the exhaust gas flows out as the flow rate of the exhaust gas increases. The exhaust gas gradually increases, and finally exhaust gas flows out from all four locations. That is, in the exhaust device (10) in this case, the cross-sectional area of the passage through which the exhaust gas is discharged from the exhaust device (10) into the atmosphere changes in four stages.

  Thus, according to the ninth, tenth, and eleventh inventions, the cross-sectional area of the passage through which the exhaust gas is discharged from the exhaust device (10) into the atmosphere is expressed by the exhaust pipe unit ( It can be changed only by adding “1” to the number of 20,40,60). Therefore, according to these inventions, the flow resistance when the exhaust gas is discharged from the exhaust device (10) can be finely adjusted according to the flow rate of the exhaust gas.

  In the tenth aspect of the invention, the spacing member (30) of the upstream exhaust pipe unit (20) is integrally formed with the outer exhaust pipe (41) of the downstream exhaust pipe unit (40). Yes. For this reason, the number of parts constituting the exhaust device (10) can be reduced, and the structure of the exhaust device (10) can be simplified.

FIG. 1 is a partial cross-sectional view illustrating a vertical cross section of the exhaust device according to the first embodiment. FIG. 2 is a partial cross-sectional view illustrating a vertical cross section of the back pressure regulator of the first embodiment. FIG. 3 is a longitudinal sectional view of the back pressure regulator of the first embodiment. FIG. 4 is a cross-sectional view showing a vertical cross section of the back pressure regulator of the first embodiment and a gas flow. FIG. 5 is a cross-sectional view showing a vertical cross section of the back pressure regulator of the first embodiment and a gas flow. FIG. 6 is a cross-sectional view showing a vertical cross section of the back pressure regulator of the first embodiment and a gas flow. FIG. 7 is a cross-sectional view showing a vertical cross section of the back pressure regulator of the first embodiment and a gas flow. FIG. 8 is a partial cross-sectional view showing a vertical cross section of the exhaust device of the second embodiment. FIG. 9 is a partial cross-sectional view illustrating a vertical cross section of the back pressure regulator of the second embodiment. FIG. 10 is a longitudinal sectional view of the back pressure regulator of the second embodiment. FIG. 11 is a longitudinal sectional view of a back pressure regulator of a modification of the second embodiment. FIG. 12 is a partial cross-sectional view illustrating a vertical cross section of the exhaust device of the third embodiment. FIG. 13 is a partial cross-sectional view showing a vertical cross section of the back pressure regulator of the third embodiment. FIG. 14 is a longitudinal sectional view of the back pressure regulator of the third embodiment. FIG. 15 is a longitudinal sectional view of a back pressure regulator of a first modification of the other embodiment.

Explanation of symbols

10 Exhaust system
15 Back pressure regulator
16 Expansion room
17 Sub exhaust pipe (communication pipe)
18 Wind shield pipe (tubular member)
19 Container-like member (blocking member)
20,40,60,80,100,120 Exhaust pipe unit
21,41,61,81,101,121 Outer exhaust pipe
22,42,62,82,102,122 Inner exhaust pipe
23,43,63,83,103,123 Cylindrical gap
24,44,64,84,104,124 Opening for communication
30,50,70,90,110,130 Spacer member (Spacing member)
31,51,71,91,111,131 Pipe section
32,52,72 Annular protrusion
33,53,73 cutout
218 Outlet side blocking member (blocking member)

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. In addition, embodiment described below is an essentially preferable illustration, Comprising: It does not intend restrict | limiting the range of this invention, its application thing, or its use.

Embodiment 1 of the Invention
A first embodiment of the present invention will be described. The exhaust device (10) of the present embodiment is for a passenger car. The exhaust device (10) is intended for a reciprocating engine (internal combustion engine) having a displacement of about 2000 cc.

  As shown in FIG. 1, the exhaust device (10) of the present embodiment includes a silencer (211) and a back pressure adjuster (15). The exhaust device (10) is connected to the end of an exhaust pipe extending from the engine.

<Structure of silencer>
The silencer (211) will be described with reference to FIG. The silencer (211) includes a cylindrical outer cylinder (215) whose both ends are closed, and an inner pipe (220) accommodated in the internal space of the outer cylinder (215). The material of the outer tube (215) and the material of the inner tube (220) are both stainless steel.

  The outer cylinder (215) includes a main body cylinder (216), an inlet side blocking member (217), and an outlet side blocking member (218). The main body cylinder (216) is a cylindrical member having both ends opened. The outer cylinder (215) has an outer diameter of about 180 mm and a length of about 400 mm. The inlet side blocking member (217) is formed in a flat disk shape, and its outer diameter is equal to the outer diameter of the main body cylinder (216). The outlet side blocking member (218) is formed in a conical shape whose diameter increases from the front end side of the main body tube (216) toward the rear end side (from the left end side to the right end side in FIG. 1). The main cylinder (216) is welded with an inlet side blocking member (217) so as to close the front end (left end in FIG. 1), and is closed with an outlet side blocking member (218) so as to close the rear end (right end in FIG. 1). Are welded. The axis of the inlet side closing member (217) and the outlet side closing member (218) substantially coincides with the axis of the main body tube (216).

  The inner pipe (220) is a straight circular pipe. In the inner pipe (220), the inner space is a single passage extending from one end of the inner pipe (220) to the other end, and the exhaust gas flows through the passage. The inner tube (220) of this embodiment has an inner diameter of about 40 mm. The inner diameter of the inner tube (220) is constant over the entire length of the inner tube (220).

  The inner pipe (220) is provided in the outer cylinder (215) in such a posture that its axis substantially coincides with the axis of the outer cylinder (215). The inlet end of the inner pipe (220) extends through the inlet side blocking member (217) of the outer cylinder (215) to the outside of the outer cylinder (215). On the other hand, the outlet end of the inner pipe (220) is fitted into a through hole formed in the central portion of the outlet-side closing member (218) and joined to the outlet-side closing member (218). The inner pipe (220) is formed integrally with the first outer exhaust pipe (21) of the first exhaust pipe unit (20). The first outer exhaust pipe (21) is formed to be continuous with the outlet end of the inner pipe (220). The details of the exhaust pipe unit (20, 40, 60) will be described later.

  A large number of side surface through holes (231 to 234) are opened on the side surface of the inner tube (220). Specifically, in the inner tube (220), the first perforated region (221), the second perforated region (222), the third perforated region (223), and the fourth perforated region (224) (220) are formed in a line in order from the inlet end (left end in FIG. 1) to the outlet end (right end in FIG. 1). The lengths of the perforated areas (221 to 224) have the same value.

  In each of the perforated regions (221 to 224), a large number of side surface through holes (231 to 234) are regularly opened on the side surface (that is, the outer peripheral surface) of the inner tube (220). Specifically, in each perforated region (221 to 224), a plurality of side surface through holes (231 to 234) are regularly formed in the circumferential direction and the axial direction of the inner tube (220). The arrangement of the side surface through holes (231 to 234) in each of the perforated regions (221 to 224) is a staggered arrangement in which the distance between the centers of the two adjacent side surface through holes (231 to 234) is constant.

  In the inner pipe (220), the diameters of the side surface through holes (231 to 234) that open to the perforated areas (221 to 224) are different from each other. In the inner pipe (220), the diameter of the side through-holes (231 to 234) opened there is smaller in the perforated area (221 to 224) closer to the outlet end. Further, in the inner pipe (220), the distance between the centers of the two adjacent side surface through holes (231 to 234) (that is, the side surface through holes (231 to 234) is closer to the perforated region (221 to 224) closer to the outlet end. ) Pitch) is narrower.

  In the inner tube (220), a plurality of communication holes (235) are regularly formed in the region closer to the inlet end (closer to the left end in FIG. 1) of the inner tube (220) than the first perforated region (221). It is a communication area (225). The communication hole (235) is a circular hole that penetrates the inner tube (220).

  A joint member (246) is inserted into the inlet end of the inner pipe (220). The joint member (246) is a relatively short straight pipe having an outer diameter substantially equal to the inner diameter of the inner pipe (220). In addition, one end (the left end portion in FIG. 1) of the joint member (246) is an enlarged diameter portion (247) whose outer diameter and inner diameter are larger than those of the other portions. Although not shown, an exhaust pipe extending from the engine is connected to the enlarged diameter portion (247).

  Three conical plates (241 to 243) are attached to the inner tube (220). The shape of each conical plate (241 to 243) is substantially the same as the shape of the outlet side blocking member (218) of the outer cylinder (215). Specifically, each conical plate (241 to 243) is formed in a conical shape whose diameter increases from the inlet end side of the inner tube (220) toward the outlet end side (from the left end side to the right end side in FIG. 1). And arranged coaxially with the inner tube (220). In each conical plate (241 to 243), the inner diameter of the end on the small diameter side (the left end in the figure) is substantially equal to the outer diameter of the inner tube (220). Welded to tube (220). In each conical plate (241 to 243), the outer diameter of the large diameter end (the right end in the figure) is substantially equal to the inner diameter of the main cylinder (216) of the outer cylinder (215). The end on the large diameter side is in contact with the inner peripheral surface of the main body cylinder (216).

  The three conical plates (241 to 243) are arranged at equal intervals in the axial direction of the inner tube (220). The end portion on the small diameter side of the first conical plate (241) is joined to the vicinity of the boundary between the first perforated region (221) and the communication region (225). The end portion on the small diameter side of the second conical plate (242) is joined to a middle portion of the second perforated region (222). The end portion on the small diameter side of the third conical plate (243) is joined to an intermediate portion of the third perforated region (223).

  In the silencer (211), the space (212) outside the inner tube (220) of the inner space of the outer cylinder (215) is an empty space (that is, a cavity) in which nothing is filled. Yes. That is, in the silencer (211), the space (212) formed between the outer tube (215) and the inner tube (220) is not filled with a sound absorbing material such as glass wool. In the silencer (211), the space (212) in the outer cylinder (215) is partitioned by three conical plates (241 to 243).

<Structure of back pressure regulator>
The back pressure regulator (15) will be described with reference to FIGS. The back pressure regulator (15) includes three exhaust pipe units (20, 40, 60). The back pressure regulator (15) is provided with a wind shield pipe (18) that is a tubular member.

  The three exhaust pipe units (20, 40, 60) are arranged in a straight line. Specifically, in the back pressure regulator (15), the first exhaust pipe unit (20), the second exhaust pipe unit (40), and the third exhaust gas flow are sequentially arranged from the upstream side to the downstream side of the exhaust gas flow. An exhaust pipe unit (60) is provided. Each exhaust pipe unit (20,40,60) includes an outer exhaust pipe (21,41,61), an inner exhaust pipe (22,42,62), and a spacer member (30,50, 70). The outer exhaust pipe (21, 41, 61) and the inner exhaust pipe (22, 42, 62) are each formed in a straight circular tube. On the other hand, the spacer member (30, 50, 70) is formed in a ring shape or a short circular tube shape. The materials of the outer exhaust pipe (21, 41, 61), the inner exhaust pipe (22, 42, 62), and the spacer member (30, 50, 70) are all stainless steel.

  The outer exhaust pipe (21, 41, 61), the inner exhaust pipe (22, 42, 62), and the spacer member (30, 50, 70) constituting each exhaust pipe unit (20, 40, 60) are all Are arranged on the same axis. As will be described later, the inner diameters of the outer exhaust pipe (21, 41, 61) and the inner exhaust pipe (22, 42, 62) provided in each exhaust pipe unit (20, 40, 60) The one arranged on the downstream side of the flow is smaller.

  Each spacer member (30, 50, 70) includes a circular pipe portion (31, 51, 71) and an annular protrusion (32, 52, 72). The circular pipe portions (31, 51, 71) are formed in a relatively short circular tube shape. The annular protrusion (32, 52, 72) is formed continuously from the tip (right end in FIG. 3) of the circular pipe (31, 51, 71). The annular protrusion (32, 52, 72) is formed over the entire circumference of the circular pipe part (31, 51, 71), and is formed from the side surface of the tip part of the circular pipe part (31, 51, 71). Projects outward. That is, the outer diameter of the annular protrusion (32, 52, 72) is larger than the outer diameter of the circular pipe (31, 51, 71).

  The first exhaust pipe unit (20) includes a first outer exhaust pipe (21), a first inner exhaust pipe (22), and a first spacer member (30) one by one.

  The first outer exhaust pipe (21) has an inner diameter that is smaller than the inner diameter of the inner pipe (220) of the silencer (211) and an outer diameter that is smaller than the outer diameter of the inner pipe (220). The first outer exhaust pipe (21) is disposed coaxially with the inner pipe (220) of the silencer (211). The base end (left end in FIG. 3) of the first outer exhaust pipe (21) is continuous with the outlet end (right end in FIG. 3) of the inner pipe (220).

  The inner diameter of the first inner exhaust pipe (22) is smaller than the inner diameter of the first outer exhaust pipe (21), and the outer diameter thereof is smaller than the outer diameter of the first outer exhaust pipe (21). The first inner exhaust pipe (22) is arranged coaxially with the first outer exhaust pipe (21). The base end (left end in FIG. 3) of the first inner exhaust pipe (22) is inserted into the first outer exhaust pipe (21) from the distal end side of the first outer exhaust pipe (21). The base end of the first inner exhaust pipe (22) is located near the center in the axial direction of the first outer exhaust pipe (21), and the tip (right end in the figure) is the first outer exhaust pipe (21). Projects from the tip.

  Between the outer peripheral surface of the portion of the first inner exhaust pipe (22) inserted into the first outer exhaust pipe (21) and the inner peripheral surface of the first outer exhaust pipe (21), a cylindrical first A cylindrical gap (23) is formed. The width of the first cylindrical gap (23) (that is, the distance between the outer peripheral surface of the first inner exhaust pipe (22) and the inner peripheral surface of the first outer exhaust pipe (21)) is constant over its entire length. At the same time, it is constant over the entire circumference of the first inner exhaust pipe (22) and the first outer exhaust pipe (21).

  The circular pipe portion (31) of the first spacer member (30) has an inner diameter equal to the outer diameter of the first inner exhaust pipe (22), and the outer diameter is equal to the inner diameter of the first outer exhaust pipe (21). It has become. Further, the annular protrusion (32) of the first spacer member (30) has an outer diameter larger than the inner diameter of the first outer exhaust pipe (21). The first spacer member (30) has a circular pipe portion (31) inserted into the first cylindrical gap (23) from the front end side of the first outer exhaust pipe (21). In this state, the circular pipe portion (31) of the first spacer member (30) has an inner peripheral surface that is in contact with the outer peripheral surface of the first inner exhaust pipe (22) over the entire circumference, and the outer peripheral surface is the entire circumference. Over the inner peripheral surface of the first outer exhaust pipe (21). Accordingly, the first cylindrical gap (23) is closed at the tip end side (right end side in FIG. 3) by the circular pipe portion (31). In this state, the annular protrusion (32) of the first spacer member (30) is exposed from the tip of the first outer exhaust pipe (21), and its end surface is the first outer exhaust pipe (21). It is in contact with the tip surface.

  A first communication opening (24) is formed in the first outer exhaust pipe (21). The first communication opening (24) is a circular through hole formed in a portion near the tip of the first outer exhaust pipe (21). In the first outer exhaust pipe (21), a plurality of first communication openings (24) are formed in a line in the circumferential direction of the first outer exhaust pipe (21). The plurality of first communication openings (24) are arranged at equal intervals in the circumferential direction of the first outer exhaust pipe (21). In the first outer exhaust pipe (21), the first communication opening (24) is slightly outside the first end (left end in FIG. 3) of the circular pipe portion (31) of the first spacer member (30). It is provided near the base end of the exhaust pipe (21). That is, the first communication opening (24) is formed in a portion of the first outer exhaust pipe (21) that overlaps the first inner exhaust pipe (22), and the tip of the first cylindrical gap (23) (see FIG. The right end of

  The second exhaust pipe unit (40) includes a second outer exhaust pipe (41), a second inner exhaust pipe (42), and a second spacer member (50) one by one.

  The inner diameter of the second outer exhaust pipe (41) is equal to the outer diameter of the first inner exhaust pipe (22), and the outer diameter is smaller than the outer diameter of the first outer exhaust pipe (21). The second outer exhaust pipe (41) is disposed coaxially with the first outer exhaust pipe (21) and the first inner exhaust pipe (22). The distal end portion of the first inner exhaust pipe (22) is inserted into the second outer exhaust pipe (41) from the base end side (left end side in FIG. 3). The proximal end of the second outer exhaust pipe (41) is in contact with the distal end surface of the first spacer member (30).

  The inner diameter of the second inner exhaust pipe (42) is smaller than the inner diameter of the first inner exhaust pipe (22), and the outer diameter thereof is smaller than the inner diameter of the second outer exhaust pipe (41). The outer diameter of the second inner exhaust pipe (42) is equal to the inner diameter of the first inner exhaust pipe (22). The second inner exhaust pipe (42) is arranged coaxially with the second outer exhaust pipe (41). The base end (left end in FIG. 3) of the second inner exhaust pipe (42) is inserted into the second outer exhaust pipe (41) from the distal end side of the second outer exhaust pipe (41). The base end of the second inner exhaust pipe (42) is located slightly closer to the base end (left end in the figure) than the center in the axial direction of the second outer exhaust pipe (41). The base end surface of the second inner exhaust pipe (42) is separated from the distal end surface of the first inner exhaust pipe (22) by a predetermined distance. The tip (the right end in the figure) of the second inner exhaust pipe (42) protrudes from the tip of the second outer exhaust pipe (41).

  Between the outer peripheral surface of the portion inserted into the second outer exhaust pipe (41) of the second inner exhaust pipe (42) and the inner peripheral surface of the second outer exhaust pipe (41), a cylindrical second A cylindrical gap (43) is formed. The width of the second cylindrical gap (43) (that is, the distance between the outer peripheral surface of the second inner exhaust pipe (42) and the inner peripheral surface of the second outer exhaust pipe (41)) is constant over its entire length. At the same time, it is constant over the entire circumference of the second inner exhaust pipe (42) and the second outer exhaust pipe (41). As described above, there is a gap between the front end surface (the right end surface in FIG. 3) of the first inner exhaust pipe (22) and the base end surface (the left end surface in FIG. 3) of the second inner exhaust pipe (42). Is provided. For this reason, the second cylindrical gap (43) communicates with the space inside the first inner exhaust pipe (22).

  The inner diameter of the circular pipe portion (51) of the second spacer member (50) is equal to the outer diameter of the second inner exhaust pipe (42), and the outer diameter is equal to the inner diameter of the second outer exhaust pipe (41). It has become. Further, the annular protrusion (52) of the second spacer member (50) has an outer diameter larger than the inner diameter of the second outer exhaust pipe (41). As for the 2nd spacer member (50), the circular pipe part (51) is inserted from the front end side of the 2nd outside exhaust pipe (41) into the 2nd cylindrical crevice (43). In this state, the circular pipe portion (51) of the second spacer member (50) has an inner peripheral surface that is in contact with the outer peripheral surface of the second inner exhaust pipe (42) over the entire circumference, and the outer peripheral surface is the entire circumference. It is in contact with the inner peripheral surface of the second outer exhaust pipe (41). Accordingly, the second cylindrical gap (43) is closed at the tip end side (right end side in FIG. 3) by the circular pipe portion (51). In this state, the annular protrusion (52) of the second spacer member (50) is exposed from the tip of the second outer exhaust pipe (41), and its end surface is the second outer exhaust pipe (41). It is in contact with the tip surface.

  A second communication opening (44) is formed in the second outer exhaust pipe (41). The second communication opening (44) is a circular through hole formed in a portion near the tip of the second outer exhaust pipe (41). In the second outer exhaust pipe (41), a plurality of second communication openings (44) are formed in a line in the circumferential direction of the second outer exhaust pipe (41). The plurality of second communication openings (44) are arranged at equal intervals in the circumferential direction of the second outer exhaust pipe (41). In the second outer exhaust pipe (41), the second communication opening (44) is slightly second outside the base end (left end in FIG. 3) of the circular pipe portion (51) of the second spacer member (50). It is provided near the base end of the exhaust pipe (41). That is, the second communication opening (44) is formed in a portion of the second outer exhaust pipe (41) that overlaps the second inner exhaust pipe (42), and the tip of the second cylindrical gap (43) (see FIG. The right end of

  The third exhaust pipe unit (60) includes a third outer exhaust pipe (61), a third inner exhaust pipe (62), and a third spacer member (70) one by one.

  The inner diameter of the third outer exhaust pipe (61) is equal to the outer diameter of the second inner exhaust pipe (42), and the outer diameter is smaller than the outer diameter of the second outer exhaust pipe (41). The third outer exhaust pipe (61) is arranged coaxially with the second outer exhaust pipe (41) and the second inner exhaust pipe (42). Specifically, the third outer exhaust pipe (61) is attached to a portion of the second inner exhaust pipe (42) protruding from the tip of the second outer exhaust pipe (41). That is, the distal end portion of the second inner exhaust pipe (42) is inserted into the third outer exhaust pipe (61) from the base end side (left end side in FIG. 3). The base end surface of the third outer exhaust pipe (61) is in contact with the distal end surface of the second spacer member (50).

  The inner diameter of the third inner exhaust pipe (62) is smaller than the inner diameter of the second inner exhaust pipe (42), and the outer diameter thereof is smaller than the inner diameter of the third outer exhaust pipe (61). The outer diameter of the third inner exhaust pipe (62) is equal to the inner diameter of the second inner exhaust pipe (42). The third inner exhaust pipe (62) is arranged coaxially with the third outer exhaust pipe (61). The base end (left end in FIG. 3) of the third inner exhaust pipe (62) is inserted into the third outer exhaust pipe (61) from the distal end side of the third outer exhaust pipe (61). The proximal end of the third inner exhaust pipe (62) is located slightly closer to the proximal end (left end in the figure) than the axial center of the third outer exhaust pipe (61). The base end surface of the third inner exhaust pipe (62) is separated from the distal end surface of the second inner exhaust pipe (42) by a predetermined distance. The distance between the proximal end face of the third inner exhaust pipe (62) and the distal end face of the second inner exhaust pipe (42) is the same as the proximal end face of the second inner exhaust pipe (42) and the distal end face of the first inner exhaust pipe (22). Is equal to the interval. The tip of the third inner exhaust pipe (62) (the right end in the figure) protrudes from the tip of the second outer exhaust pipe (41).

  Between the outer peripheral surface of the portion inserted into the third outer exhaust pipe (61) of the third inner exhaust pipe (62) and the inner peripheral surface of the third outer exhaust pipe (61), a cylindrical third A cylindrical gap (63) is formed. The width of the third cylindrical gap (63) (that is, the distance between the outer peripheral surface of the third inner exhaust pipe (62) and the inner peripheral surface of the third outer exhaust pipe (61)) is constant over its entire length. At the same time, it is constant over the entire circumference of the third inner exhaust pipe (62) and the third outer exhaust pipe (61). As described above, there is a gap between the distal end surface (the right end surface in FIG. 3) of the second inner exhaust pipe (42) and the base end surface (the left end surface in FIG. 3) of the third inner exhaust pipe (62). Is provided. For this reason, the third cylindrical gap (63) communicates with the space inside the second inner exhaust pipe (42).

  The circular pipe portion (71) of the third spacer member (70) has an inner diameter equal to the outer diameter of the third inner exhaust pipe (62), and the outer diameter is equal to the inner diameter of the third outer exhaust pipe (61). It has become. Further, the outer diameter of the annular protrusion (72) of the third spacer member (70) is larger than the inner diameter of the third outer exhaust pipe (61). The third spacer member (70) has a circular pipe portion (71) inserted into the third cylindrical gap (63) from the distal end side of the third outer exhaust pipe (61). In this state, the circular pipe portion (71) of the third spacer member (70) has an inner peripheral surface that is in contact with the outer peripheral surface of the third inner exhaust pipe (62) over the entire circumference, and the outer peripheral surface is the entire circumference. Over the inner peripheral surface of the third outer exhaust pipe (61). Accordingly, the third cylindrical gap (63) is closed at the tip end side (right end side in FIG. 3) by the circular pipe portion (71). Further, in this state, the annular protrusion (72) of the third spacer member (70) is exposed from the tip of the third outer exhaust pipe (61), and its end surface is the third outer exhaust pipe (61). It is in contact with the tip surface.

  A third communication opening (64) is formed in the third outer exhaust pipe (61). The third communication opening (64) is a circular through hole formed in a portion near the tip of the third outer exhaust pipe (61). In the third outer exhaust pipe (61), a plurality of third communication openings (64) are formed in a line in the circumferential direction of the third outer exhaust pipe (61). The plurality of third communication openings (64) are arranged at equal intervals in the circumferential direction of the third outer exhaust pipe (61). In the third outer exhaust pipe (61), the third communication opening (64) is slightly outside of the third outer side of the base end (left end in FIG. 3) of the circular pipe portion (71) of the third spacer member (70). It is provided near the base end of the exhaust pipe (61). That is, the third communication opening (64) is formed in a portion of the third outer exhaust pipe (61) that overlaps with the third inner exhaust pipe (62), and the tip of the third cylindrical gap (63) (see FIG. The right end of

  The wind shield pipe (18) is a straight circular pipe made of stainless steel. The wind shield pipe (18) is provided so as to surround all the exhaust pipe units (20, 40, 60). Specifically, the axis of the wind shield pipe (18) includes the outer exhaust pipe (21, 41, 61) and the inner exhaust pipe (22, 42, 62) constituting each exhaust pipe unit (20, 40, 60). It almost coincides with the axis of Further, the base end (the left end in FIG. 3) of the wind shield pipe (18) is joined to the outlet side blocking member (218).

  The inner diameter of the wind shield pipe (18) is larger than the outer diameter of the first outer exhaust pipe (21). The first outer exhaust pipe (21) has the largest diameter among the three outer exhaust pipes (21, 41, 61). Therefore, the inner peripheral surface (that is, the inner side surface) of the wind shield pipe (18) faces the outer peripheral surfaces of all the outer exhaust pipes (21, 41, 61) at a predetermined interval. That is, the inner peripheral surface of the wind shield pipe (18) faces the communication openings (24, 44, 64) formed in all the outer exhaust pipes (21, 41, 61).

  Further, the inner diameter of the wind shield pipe (18) is set so that the distance between the inner peripheral surface of the wind shield pipe (18) and the outer peripheral surface of each outer exhaust pipe (21, 41, 61) is sufficiently secured. 1 It is set to a value somewhat larger than the outer diameter of the outer exhaust pipe (21). The reason for setting the inner diameter of the wind shield pipe (18) to such a value is that the flow of exhaust gas flowing out from each communication opening (24, 44, 64) is obstructed by the wind shield pipe (18). It is necessary to prevent.

  The length of the wind shield pipe (18) is set to such a value that the entire exhaust pipe unit (20, 40, 60) is covered by the wind shield pipe (18). For this reason, in FIG. 3, the right end (tip) of the wind shield pipe (18) is located further to the right than the right end (tip) of the third inner exhaust pipe (62).

  Only the front end (right end in the figure) of the wind shield pipe (18) is an open end, and the base end is closed by the outlet side blocking member (218). That is, in this embodiment, the outlet side blocking member (218) constituting the outer cylinder (215) of the silencer (211) also serves as a blocking member for closing the proximal end of the wind shield tube (18). .

-Noise reduction effect of silencer-
The noise reduction effect of the silencer (211) will be described with reference to FIG.

  The exhaust gas discharged from the engine flows into the silencer (211) through the exhaust pipe (80). The exhaust gas flowing into the silencer (211) from the exhaust pipe (80) flows into the space inside the inner pipe (220). The exhaust gas that has flowed into the inner pipe (220) includes the communication region (225), the first perforation region (221), the second perforation region (222), the third perforation region (223), and the fourth The sound passes through the perforated area (224) in turn and is silenced during that time.

  In the communication area (225) and each perforation area (221 to 224), the pressure fluctuation of the exhaust gas flowing therethrough passes through the communication hole (235) and the side through holes (231 to 234) and is outside the inner pipe (220). It is transmitted to. A part of the exhaust gas expands when it flows into the space (212) outside the inner pipe (220) through the communication hole (235) and the side through holes (231 to 234), thereby increasing the pressure of the exhaust gas. The fluctuation is attenuated.

  As described above, in each of the perforated regions (221 to 224) formed in the inner pipe (220), the side through holes (231 to 234) formed therein are located closer to the downstream side of the exhaust gas flow. The diameter of is smaller. On the other hand, the frequency of the sound wave that can pass through the side surface through holes (231 to 234) decreases as the side surface through holes (231 to 234) increase. For this reason, in the process in which the exhaust gas passes through the inner pipe (220), the pressure fluctuation of the exhaust gas is attenuated in order from the component having the lowest frequency.

  Furthermore, in the silencer (211) of the present embodiment, conical plates (241 to 243) are provided in the space (212) between the outer tube (215) and the inner tube (220). Then, the action of the conical plates (241 to 243) promotes the attenuation of the pressure fluctuation of the exhaust gas transmitted to the space (212) between the outer cylinder (215) and the inner pipe (220).

  That is, the sound wave that has passed through the side surface through holes (231 to 234) and has been emitted to the outside of the inner tube (220) is reflected by the inner peripheral surface of the conical plate (241 to 243), and its traveling direction is changed. For this reason, it becomes difficult for the sound wave that has been emitted to the outside of the inner tube (220) to return to the inside of the inner tube (220) again through the side surface through holes (231 to 234). Furthermore, in the space (212) outside the inner tube (220), the sound wave strikes the conical plates (241 to 243) and is reflected, so that there is a sound wave traveling in various directions. For this reason, in the space (212) outside the inner tube (220), the sound waves are also attenuated when the sound waves having different traveling directions interfere with each other and cancel each other.

-Back pressure adjustment action of back pressure regulator-
The back pressure adjusting action of the back pressure adjuster (15) will be described with reference to FIGS.

  FIG. 4 shows the flow of exhaust gas in the back pressure regulator (15) when the engine is idling (the engine speed is around 600 rpm). That is, the flow of the exhaust gas shown in the figure is in a state where the flow rate of the exhaust gas discharged from the engine is the lowest.

  As shown in FIG. 4, when the flow rate of the exhaust gas is substantially the smallest, the exhaust gas flows out only from the first communication opening (24) formed in the first exhaust pipe unit (20). That is, the exhaust gas flowing into the first outer exhaust pipe (21) from the inner pipe (220) of the silencer (211) flows into the first cylindrical gap (23) and passes through the first communication opening (24). Released into the atmosphere.

  Further, in this state, the space inside each of the inner exhaust pipes (22, 42, 62), the second cylindrical gap (43), and the third cylindrical gap (63) are in a negative pressure state (ie, a large pressure). The pressure is lower than the atmospheric pressure). Therefore, in the back pressure regulator (15), air is sucked into the tip of the third inner exhaust pipe (62), the third communication opening (64), and the second communication opening (44).

  The air sucked into the distal end of the third inner exhaust pipe (62) flows from the distal end of the third inner exhaust pipe (62) toward the proximal end side, and flows into the second inner exhaust pipe (42). The air sucked into the third communication opening (64) flows into the second inner exhaust pipe (42) through the third cylindrical gap (63). The air that has flowed into the second inner exhaust pipe (42) flows from the distal end of the second inner exhaust pipe (42) toward the base end side, and then flows into the first inner exhaust pipe (22). The air sucked into the second communication opening (44) flows into the first inner exhaust pipe (22) through the second cylindrical gap (43). The air that has flowed into the first inner exhaust pipe (22) flows from the distal end of the first inner exhaust pipe (22) toward the proximal end side, and then merges with the exhaust gas to the first cylindrical gap (23). It flows in and flows out to the outside of the first outer exhaust pipe (21) through the first communication opening (24).

  In the state shown in FIG. 4, as the engine speed increases and the exhaust gas flow rate gradually increases, the flow rate of the exhaust gas flowing out from the first communication opening (24) gradually increases, The flow rate of air sucked into the communication opening (44) gradually decreases. When the flow rate of the exhaust gas reaches a certain level or more, as shown in FIG. 5, the exhaust gas flows out from both the first communication opening (24) and the second communication opening (44).

  In the state shown in FIG. 5, part of the exhaust gas flowing from the inner pipe (220) of the silencer (211) into the first outer exhaust pipe (21) passes through the first cylindrical gap (23). The air is discharged from the first communication opening (24) into the atmosphere, and the remainder passes through the first inner exhaust pipe (22) and then passes through the second cylindrical gap (43) from the second communication opening (44) to the atmosphere. Released.

  Even in this state, the space inside the second inner exhaust pipe (42) and the third inner exhaust pipe (62) and the third cylindrical gap (63) are still in the negative pressure state. For this reason, in the back pressure regulator (15), air is sucked into the tip of the third inner exhaust pipe (62) and the third communication opening (64).

  The air sucked into the tip of the third inner exhaust pipe (62) and the air sucked into the third communication opening (64) flow in the same manner as shown in FIG. 42). The air that has flowed into the second inner exhaust pipe (42) flows from the distal end of the second inner exhaust pipe (42) toward the base end, and merges with the exhaust gas that has passed through the first inner exhaust pipe (22). It flows into the second cylindrical gap (43) and flows out of the second outer exhaust pipe (41) through the second communication opening (44).

  In the state shown in FIG. 5, the exhaust gas flowing out from the first communication opening (24) and the second communication opening (44) increases as the engine speed increases and the flow rate of the exhaust gas gradually increases. Simultaneously with the increase in the flow rate, the flow rate of the air sucked into the third communication opening (64) gradually decreases. When the flow rate of the exhaust gas reaches a certain level or more, as shown in FIG. 6, not only from the first communication opening (24) and the second communication opening (44) but also from the third communication opening (64). The exhaust gas flows out.

  In the state shown in FIG. 6, a part of the exhaust gas flowing from the inner pipe (220) of the silencer (211) into the first outer exhaust pipe (21) passes through the first cylindrical gap (23). It is discharged into the atmosphere from the first communication opening (24), and the remainder flows into the first inner exhaust pipe (22). A portion of the exhaust gas that has passed through the first inner exhaust pipe (22) passes through the second cylindrical gap (43) and is released into the atmosphere from the second communication opening (44), and the remainder remains on the second inner side. After passing through the exhaust pipe (42), it passes through the third cylindrical gap (63) and is released into the atmosphere from the third communication opening (64).

  Even in this state, the space inside the third inner exhaust pipe (62) is still in the negative pressure state. For this reason, in the back pressure regulator (15), air is sucked into the tip of the third inner exhaust pipe (62).

  The air sucked into the distal end of the third inner exhaust pipe (62) flows from the distal end of the third inner exhaust pipe (62) toward the base end side, and the exhaust gas that has passed through the second inner exhaust pipe (42) It merges, flows into the third cylindrical gap (63), flows out of the second outer exhaust pipe (41) through the third communication opening (64).

  In the state shown in FIG. 6, as the engine speed increases and the exhaust gas flow rate gradually increases, the first communication opening (24), the second communication opening (44), and the third communication opening. As the flow rate of the exhaust gas flowing out from the opening (64) gradually increases, the flow rate of the air sucked into the tip of the third inner exhaust pipe (62) gradually decreases. When the flow rate of the exhaust gas reaches a certain level or more, as shown in FIG. 7, the first communication opening (24), the second communication opening (44), the third communication opening (64), and the third communication opening The exhaust gas flows out from the tip of the inner exhaust pipe (62).

  In the state shown in FIG. 7, a part of the exhaust gas flowing from the inner pipe (220) of the silencer (211) into the first outer exhaust pipe (21) passes through the first cylindrical gap (23). It is discharged into the atmosphere from the first communication opening (24), and the remainder flows into the first inner exhaust pipe (22). A portion of the exhaust gas that has passed through the first inner exhaust pipe (22) passes through the second cylindrical gap (43) and is released into the atmosphere from the second communication opening (44), and the remainder remains on the second inner side. It flows into the exhaust pipe (42). Part of the exhaust gas that has flowed into the second inner exhaust pipe (42) passes through the third cylindrical gap (63) and is released into the atmosphere from the third communication opening (64), and the remainder remains on the third inner side. It passes through the exhaust pipe (62) and is released into the atmosphere from the tip of the third inner exhaust pipe (62).

  Thus, in the back pressure regulator (15) of the present embodiment, the locations where the exhaust gas can be released into the atmosphere are the first communication opening (24), the second communication opening (44), and the third communication hole. There are four locations at the tip of the common opening (64) and the third inner exhaust pipe (62). In the back pressure regulator (15), as the flow rate of the exhaust gas sent from the silencer (211) to the first outer exhaust pipe (21) increases, the number of places where the exhaust gas is released into the atmosphere increases. go. In other words, in this back pressure regulator (15), the higher the flow rate of the exhaust gas flowing into the back pressure regulator (15), the more the exhaust gas passes through the back pressure regulator (15) when it is released into the atmosphere. The cross sectional area of the passage to be increased.

  For this reason, in the back pressure regulator (15) of this embodiment, even if the flow rate of the exhaust gas changes, the flow resistance when the exhaust gas passes therethrough does not change much. Therefore, if this back pressure regulator (15) is connected to the exhaust pipe, the back pressure of the engine is kept substantially constant regardless of the engine speed (that is, regardless of the flow rate of the exhaust gas).

-Effect of Embodiment 1-
As described above, the exhaust device (10) of the present embodiment is provided with the back pressure regulator (15), and the back pressure regulator (15) includes three exhaust pipe units (20, 40, 60). Is provided. In this back pressure regulator (15), the exhaust gas flows out only from the first communication opening (24) (the state shown in FIG. 4), the first communication opening (24), and the second communication opening. The exhaust gas flows out from two locations of the opening (44) (the state shown in FIG. 5), the first communication opening (24), the second communication opening (44), and the third communication opening (64). A state in which exhaust gas flows out from three locations (the state shown in FIG. 6), a first communication opening (24), a second communication opening (44), a third communication opening (64), and a third inner exhaust pipe The state of exhaust gas flowing out from the four locations at the tip of (62) (the state shown in FIG. 7) is automatically switched according to the flow rate of exhaust gas flowing into the back pressure regulator (15).

  As described above, according to the back pressure regulator (15) of the present embodiment, the cross-sectional area of the passage through which exhaust gas is discharged from the back pressure regulator (15) into the atmosphere is determined by a mechanical mechanism such as a valve. It is possible to increase or decrease according to the flow rate of the exhaust gas without using any special means. For this reason, according to the back pressure regulator (15) of this embodiment, it becomes possible to set the flow resistance of the exhaust gas in the back pressure regulator (15) to an appropriate value according to the flow rate of the exhaust gas. . As a result, even if the engine speed changes and the flow rate of the exhaust gas changes, the back pressure of the engine can be kept substantially constant, and the loss of the engine due to exhaust gas discharge can be reduced.

  Moreover, in each exhaust pipe unit (20, 40, 60) provided in the back pressure regulator (15) of this embodiment, the circular pipe part (31, 51, 71) of the spacer member (30, 50, 70) Is inserted between the outer exhaust pipe (21, 41, 61) and the inner exhaust pipe (22, 42, 62), so that the outer exhaust pipe (21, 41, 61) and the inner exhaust pipe (22, 42, 62) are inserted. ) Relative positioning is performed. In each exhaust pipe unit (20, 40, 60), the distance between the outer exhaust pipe (21, 41, 61) and the inner exhaust pipe (22, 42, 62) is the distance between the spacer members (30, 50, 70). It becomes substantially equal to the thickness of the circular pipe portion (31, 51, 71).

  For this reason, in the back pressure regulator (15) of this embodiment, by managing the dimensional accuracy of the circular pipe part (31, 51, 71) of the spacer member (30, 50, 70), the outer exhaust pipe (21 , 41, 61) and the thickness of the cylindrical gap (23, 43, 63) formed between the inner exhaust pipe (22, 42, 62). Therefore, according to the present embodiment, the variation in the thickness of the cylindrical gap (23, 43, 63) for each product can be easily and reliably suppressed, and the performance difference for each product can be reliably reduced. .

  Further, in each exhaust pipe unit (20, 40, 60) of the present embodiment, a spacer member (30 inserted between the outer exhaust pipe (21, 41, 61) and the inner exhaust pipe (22, 42, 62). , 50, 70) is formed in a circular tube shape, and has a certain length in the axial direction thereof. That is, in each exhaust pipe unit (20, 40, 60), the circular pipe part (31, 51, 71) having a certain length in the axial direction is formed by the outer exhaust pipe (21, 41, 61) and the inner exhaust pipe. (22,42,62). Therefore, according to the present embodiment, the “displacement” between the axis of the outer exhaust pipe (21, 41, 61) and the axis of the inner exhaust pipe (22, 42, 62) can be easily and reliably reduced. Can do.

  In each exhaust pipe unit (20, 40, 60) of the present embodiment, the spacer member (30, 50, 70) is located outside the cylindrical gap (23, 43, 63) with respect to the outer exhaust pipe (21, 41, 61). Therefore, according to the present embodiment, the spacer member (21) without hindering the flow of the exhaust gas flowing from the proximal end side of the outer exhaust pipe (21, 41, 61) into the cylindrical gap (23, 43, 63). 30, 50, 70) can maintain the distance between the outer exhaust pipe (21, 41, 61) and the inner exhaust pipe (22, 42, 62).

  Moreover, in each exhaust pipe unit (20, 40, 60) of this embodiment, the annular protrusion (32, 52, 72) is formed in the spacer member (30, 50, 70), and this annular protrusion ( 32, 52, 72) abuts on the front end surface of the outer exhaust pipe (21, 41, 61). That is, when assembling the back pressure regulator (15) of the present embodiment, the circular pipe portion (31) until the annular protrusion (32, 52, 72) hits the front end surface of the outer exhaust pipe (21, 41, 61). , 51, 71) into the cylindrical gap (23, 43, 63), the relative positional relationship between the outer exhaust pipe (21, 41, 61) and the spacer member (30, 50, 70) is uniquely It will be fixed. Therefore, according to this embodiment, the spacer member (30, 50, 70) can be easily and reliably positioned with respect to the outer exhaust pipe (21, 41, 61), and the back pressure regulator (15) The labor and time required for assembly can be reduced.

  By the way, in the back pressure regulator (15) of this embodiment, to the cylindrical gap (23, 43, 63) between the outer exhaust pipe (21, 41, 61) and the inner exhaust pipe (22, 42, 62). The exhaust gas that has flowed in is blown out from the communication opening (24, 44, 64) to the sides of the outer exhaust pipe (21, 41, 61) and the inner exhaust pipe (22, 42, 62). Therefore, if there is an air flow in the vicinity of the communication opening (24,44,64), the flow of exhaust gas blown out from the communication opening (24,44,64) is obstructed by the air flow, and the back pressure is adjusted. May adversely affect the performance of the vessel (15). In particular, the exhaust device (10) of the present embodiment is mounted on an automobile, and an air flow is generated in the vicinity of the communication opening (24, 44, 64) as the automobile travels. There is a high possibility that the performance of the back pressure regulator (15) will deteriorate.

  On the other hand, in the back pressure regulator (15) of this embodiment, the periphery of all the exhaust pipe units (40, 60) is surrounded by the wind shield pipe (18), and the communication openings (24, 44, 64) ) Is less likely to generate airflow. Furthermore, in the back pressure regulator (15) of the present embodiment, the proximal end of the wind shield pipe (18) is closed by the outlet side blocking member (218) of the silencer (211). That is, in the back pressure regulator (15) of the present embodiment, only the tip of the wind shield (18) is the open end. Therefore, according to this embodiment, the air flow in the vicinity of the communication opening (24, 44, 64) can be reliably suppressed by the wind shield pipe (18), and the communication opening (24, 44, 64). The performance degradation of the back pressure regulator (15) due to the air flow in the vicinity can be reliably suppressed.

<< Embodiment 2 of the Invention >>
A second embodiment of the present invention will be described.

  As shown in FIG. 8, the exhaust device (10) of the present embodiment is obtained by changing the structure of the back pressure regulator (15) of the first embodiment. The back pressure regulator (15) of the present embodiment is different from the first embodiment in the structure of each exhaust pipe unit (20, 40, 60). Here, about the back pressure regulator (15) of this embodiment, a different point from the back pressure regulator (15) of the said Embodiment 1 is demonstrated.

  As shown in FIGS. 9 and 10, in each exhaust pipe unit (20, 40, 60) of the present embodiment, the outer exhaust pipe of the exhaust pipe unit (40, 60) disposed on the downstream side of the exhaust gas flow. (41, 61) also serves as the spacer member (30, 50) of the exhaust pipe unit (20, 40) arranged on the upstream side thereof. In other words, in each exhaust pipe unit (20, 40, 60) of the present embodiment, the spacer member (30, 50) of the exhaust pipe unit (20, 40) disposed on the upstream side of the exhaust gas flow is downstream of the exhaust pipe unit (20, 40, 60). It is formed integrally with the outer exhaust pipe (41, 61) of the exhaust pipe unit (40, 60) arranged on the side.

  The second outer exhaust pipe (41) of the second exhaust pipe unit (40) is extended to the base end side (left side in FIG. 10) as compared with the first embodiment. The portion of the second outer exhaust pipe (41) near the base end constitutes the first spacer member (30) of the first exhaust pipe unit (20).

  A plurality of notches (33) are formed in the second outer exhaust pipe (41). The notch (33) is formed by cutting a part of the second outer exhaust pipe (41) over a predetermined length from the base end of the second outer exhaust pipe (41) toward the tip. ing. Each notch (33) has the same length and the same width.

  In the second outer exhaust pipe (41), the plurality of notches (33) are formed at equal intervals in the circumferential direction of the second outer exhaust pipe (41). That is, in the portion near the base end of the second outer exhaust pipe (41), the notch (33) and the protrusion (35) remaining without being cut in the circumferential direction of the second outer exhaust pipe (41) Are arranged alternately. Moreover, in the part near the base end of the second outer exhaust pipe (41), the part extending from the base of the projection (35) to the axial direction of the second outer exhaust pipe (41) has a predetermined width. 30) the base (34).

  As described above, the first spacer member (30) formed integrally with the second outer exhaust pipe (41) includes one base (34) formed in a relatively short circular tube and a base of the base (34). A plurality of elongated protrusions (35) protruding from the end (left end in FIG. 10). Each protrusion (35) of the first spacer member (30) has a radius of curvature of the inner surface equal to the radius of curvature of the inner circumferential surface of the second outer exhaust pipe (41) (that is, half of the inner diameter) The radius of curvature of the outer surface is equal to the radius of curvature of the outer peripheral surface of the second outer exhaust pipe (41) (that is, half of the outer diameter).

  The first spacer member (30) configured by the portion near the base end of the second outer exhaust pipe (41) is provided between the first outer exhaust pipe (21) and the first inner exhaust pipe (22). It is inserted from the front end side of the outer exhaust pipe (21). Specifically, the first cylindrical gap (23) formed between the first outer exhaust pipe (21) and the first inner exhaust pipe (22) has a protrusion (35) of the first spacer member (30). ) Is inserted from the tip side. At that time, the protrusion (35) of the first spacer member (30) is inserted into the first cylindrical gap (23) up to a portion slightly closer to the root than the center in the length direction. That is, only a part of the protrusion (35) is inserted into the first cylindrical gap (23). For this reason, the cutout (33) of the first spacer member (30) is covered by the first outer exhaust pipe (21) only in a part in the length direction, and the remaining part is covered by the first outer exhaust pipe (21). It will be in the state exposed from the tip.

  Thus, in the 1st exhaust pipe unit (20) of this embodiment, a part of notch (33) of the 1st spacer member (30) is exposed from the tip of the 1st outside exhaust pipe (21). . For this reason, the first cylindrical gap (23) communicates with the outside of the first outer exhaust pipe (21) via a portion of the notch (33) exposed from the first outer exhaust pipe (21). Yes. That is, in the first exhaust pipe unit (20), the portion of the cutout (33) of the first spacer member (30) exposed from the first outer exhaust pipe (21) is the first communication opening (24). It has become.

  The third outer exhaust pipe (61) of the third exhaust pipe unit (60) is extended to the base end side (left side in FIG. 10) as compared with the first embodiment. The portion of the third outer exhaust pipe (61) near the base end constitutes the second spacer member (50) of the second exhaust pipe unit (40).

  A plurality of notches (53) are formed in the third outer exhaust pipe (61). The notch (53) is formed by cutting a part of the third outer exhaust pipe (61) from the proximal end of the third outer exhaust pipe (61) toward the tip thereof over a predetermined length. ing. Each notch (53) has the same length and the same width.

  In the third outer exhaust pipe (61), the plurality of notches (53) are formed at equal intervals in the circumferential direction of the third outer exhaust pipe (61). That is, in the portion near the base end of the third outer exhaust pipe (61), the notch (53) and the protrusion (55) remaining without being cut off in the circumferential direction of the third outer exhaust pipe (61) Are arranged alternately. Further, in the portion near the base end of the third outer exhaust pipe (61), a portion extending from the base of the projection (55) to the axial direction of the third outer exhaust pipe (61) over a predetermined width is the second spacer member ( 50) of the base (54).

  As described above, the second spacer member (50) formed integrally with the third outer exhaust pipe (61) includes one base (54) formed in a relatively short circular tube and a base of the base (54). A plurality of elongated protrusions (55) protruding from the end (left end in FIG. 10). Each protrusion (55) of the second spacer member (50) has a radius of curvature of its inner surface equal to the radius of curvature of the inner circumferential surface of the third outer exhaust pipe (61) (ie, half the inner diameter) The curvature radius of the outer surface is equal to the curvature radius of the outer peripheral surface of the third outer exhaust pipe (61) (that is, half of the outer diameter).

  The second spacer member (50) constituted by the portion near the base end of the third outer exhaust pipe (61) is inserted between the second outer exhaust pipe (41) and the second inner exhaust pipe (42). It is inserted from the front end side of the outer exhaust pipe (41). Specifically, the second cylindrical gap (43) formed between the second outer exhaust pipe (41) and the second inner exhaust pipe (42) has a protrusion (55) of the second spacer member (50). ) Is inserted from the tip side. At that time, the protrusion (55) of the second spacer member (50) is inserted into the second cylindrical gap (43) up to a portion slightly closer to the root than the center in the length direction. That is, only a part of the protrusion (55) is inserted into the second cylindrical gap (43). For this reason, the notch (53) of the second spacer member (50) is covered by the second outer exhaust pipe (41) only in a part in the length direction, and the remaining part is covered by the second outer exhaust pipe (41). It will be in the state exposed from the tip.

  Thus, in the 2nd exhaust pipe unit (40) of this embodiment, a part of notch (53) of the 2nd spacer member (50) is exposed from the tip of the 2nd outside exhaust pipe (41). . For this reason, the second cylindrical gap (43) communicates with the outside of the second outer exhaust pipe (41) via a portion of the notch (53) exposed from the second outer exhaust pipe (41). Yes. That is, in the second exhaust pipe unit (40), the portion of the cutout (53) of the second spacer member (50) exposed from the second outer exhaust pipe (41) is the second communication opening (44). It has become.

  The third spacer member (70) of the third exhaust pipe unit (60) is formed in a circular tube shape. The inner diameter of the third spacer member (70) is equal to the outer diameter of the third inner exhaust pipe (62), and the outer diameter is equal to the inner diameter of the third outer exhaust pipe (61).

  A plurality of notches (73) are formed in the third spacer member (70). The notch (73) is formed by cutting a part of the third spacer member (70) over a predetermined length from the proximal end of the third spacer member (70) toward the distal end thereof. . Each notch (73) has the same length and the same width.

  In the third spacer member (70), the plurality of notches (73) are formed at equal intervals in the circumferential direction of the third spacer member (70). That is, in the third spacer member (70), the notches (73) and the protrusions (75) remaining without being cut are alternately arranged in the circumferential direction of the third spacer member (70). Further, in the third spacer member (70), the tip end portion (the right end portion in FIG. 10) is a base portion (74).

  As described above, the third spacer member (70) includes one base (74) formed in a relatively short circular tube and a plurality of elongated protrusions protruding from the base end (left end in FIG. 10) of the base (74). Part (75). Each protrusion (75) of the third spacer member (70) has a radius of curvature of the inner surface equal to the radius of curvature of the outer peripheral surface of the third inner exhaust pipe (62) (ie, half of the outer diameter) The radius of curvature of the outer surface is equal to the radius of curvature of the inner peripheral surface of the second outer exhaust pipe (41) (that is, half of the inner diameter).

  The third inner exhaust pipe (62) is inserted between the third outer exhaust pipe (61) and the third inner exhaust pipe (62) from the distal end side of the third outer exhaust pipe (61). Specifically, the third cylindrical gap (63) formed between the third outer exhaust pipe (61) and the third inner exhaust pipe (62) has a protrusion (75) of the third spacer member (70). ) Is inserted from the tip side. At that time, the protrusion (75) of the third spacer member (70) is inserted into the third cylindrical gap (63) up to a portion slightly closer to the root than the center in the length direction. That is, only a part of the protrusion (75) is inserted into the third cylindrical gap (63). For this reason, the notch (73) of the third spacer member (70) is covered by the third outer exhaust pipe (61) only in a part in the length direction, and the remaining part is covered by the third outer exhaust pipe (61). It will be in the state exposed from the tip.

  Thus, in the 3rd exhaust pipe unit (60) of this embodiment, a part of notch (73) of the 3rd spacer member (70) is exposed from the tip of the 3rd outside exhaust pipe (61). . For this reason, the third cylindrical gap (63) communicates with the outside of the third outer exhaust pipe (61) through a portion of the notch (73) exposed from the third outer exhaust pipe (61). Yes. That is, in the third exhaust pipe unit (60), the portion of the notch (73) of the third spacer member (70) exposed from the third outer exhaust pipe (61) is the third communication opening (64). It has become.

  The back pressure regulating action of the back pressure regulator (15) of the present embodiment is the same as that of the first embodiment. That is, in the back pressure regulator (15) of the present embodiment, the exhaust gas flows out only from the first communication opening (24) (the same state as the state shown in FIG. 4), and the first communication opening ( 24) and the second communication opening (44) in a state where exhaust gas flows out (similar to the state shown in FIG. 5), the first communication opening (24) and the second communication opening (44). ) And the third communication opening (64) (the same state as that shown in FIG. 6), the first communication opening (24) and the second communication opening (44). And the state in which exhaust gas flows out from the four locations at the tip of the third communication opening (64) and the third inner exhaust pipe (62) (the same state as shown in FIG. 7) is the back pressure regulator (15 ) Automatically switches according to the flow rate of the exhaust gas flowing into.

-Effect of Embodiment 2-
In the back pressure regulator (15) of the present embodiment, the spacer member (30, 50, 70) in which the notches (33, 53, 73) are formed has a part of the notches (33, 53, 73). The outer exhaust pipe (21, 41, 61) and the inner exhaust pipe (22, 42, 62) are projected from the protruding end side of the projection (35, 55, 75) so as to be exposed from the outer exhaust pipe (21, 41, 61). ). Therefore, the cylindrical gap (23, 43, 63) formed between the outer exhaust pipe (21, 41, 61) and the inner exhaust pipe (22, 42, 62) is the spacer member (30, 50, 70). It communicates with the outside of the outer exhaust pipe (21, 41, 61) through the notches (33, 53, 73) formed in the outer wall. That is, according to this embodiment, the cylindrical gap (23, 43, 63) is inserted into the outer exhaust pipe (23, 43, 63) by inserting the spacer member (30, 50, 70) into the cylindrical gap (23, 43, 63). 21, 41, 61) can communicate with the outside.

  In the back pressure regulator (15) of the present embodiment, the second outer exhaust pipe (41) of the second exhaust pipe unit (40) is connected to the first spacer member (30) of the first exhaust pipe unit (20). The third outer exhaust pipe (61) of the third exhaust pipe unit (60) also serves as the second spacer member (50) of the second exhaust pipe unit (40). Therefore, according to this embodiment, the number of parts constituting the back pressure regulator (15) can be reduced, and the structure of the exhaust device (10) can be simplified.

-Modification of Embodiment 2-
In the back pressure regulator (15) of this embodiment, as shown in FIG. 11, the first spacer member (30) may be formed separately from the second outer exhaust pipe (41). Moreover, in the back pressure regulator (15) of this embodiment, as shown to the same figure, the 2nd spacer member (50) may be formed separately from the 3rd outer side exhaust pipe (61).

<< Embodiment 3 of the Invention >>
Embodiment 3 of the present invention will be described.

  As shown in FIG. 12, the exhaust device (10) of the present embodiment is obtained by changing the structure of the back pressure regulator (15) of the first embodiment. The back pressure regulator (15) of the present embodiment is implemented in terms of the number of exhaust pipe units (20, 40, 60, 80, 100, 120) and the structure of each exhaust pipe unit (20, 40, 60, 80, 100, 120). Different from Form 1. Here, about the back pressure regulator (15) of this embodiment, a different point from the back pressure regulator (15) of the said Embodiment 1 is demonstrated.

  As shown in FIGS. 13 and 14, the back pressure regulator (15) of this embodiment includes six exhaust pipe units (20, 40, 60, 80, 100, 120), one connection exhaust pipe (140), and Is provided. Further, in each exhaust pipe unit (20, 40, 60, 80, 100, 120), there is an outer exhaust pipe (41, 61, 81, 101, 121) of the exhaust pipe unit (40, 60, 80, 100, 120) arranged on the downstream side of the exhaust gas flow. It also serves as the spacer member (30, 50, 70, 90, 110) of the exhaust pipe unit (20, 40, 60, 80, 100) arranged on the upstream side. That is, in each exhaust pipe unit (20, 40, 60, 80, 100, 120) of this embodiment, the spacer member (30, 40) of the exhaust pipe unit (20, 40, 60, 80, 100) arranged on the upstream side of the exhaust gas flow. 50, 70, 90, 110) are integrally formed with the outer exhaust pipe (41, 61, 81, 101, 121) of the exhaust pipe unit (40, 60, 80, 100, 120) arranged on the downstream side thereof. As in the first embodiment, the spacer member (30, 50, 70, 90, 110, 130) of each exhaust pipe unit (20, 40, 60, 80, 100, 120) constitutes a spacing member.

  In the back pressure regulator (15) of the present embodiment, the connection exhaust pipe (140) is connected to the inner pipe (220) of the silencer (211). The connection exhaust pipe (140) has an inner diameter smaller than the inner diameter of the inner pipe (220) of the silencer (211) and an outer diameter smaller than the outer diameter of the inner pipe (220). The axial center of the connecting exhaust pipe (140) substantially coincides with the axial center of the inner pipe (220). The base end (left end in FIG. 14) of the connection exhaust pipe (140) is continuous with the outlet end (right end in FIG. 14) of the inner pipe (220).

  As in the first embodiment, the first exhaust pipe unit (20) includes the first outer exhaust pipe (21), the first inner exhaust pipe (22), and the first spacer member (30) one by one. I have. However, in the back pressure regulator (15) of the present embodiment, the first spacer member (30) is formed integrally with a second outer exhaust pipe (41) described later.

  The first outer exhaust pipe (21) has an inner diameter equal to the outer diameter of the connection exhaust pipe (140). The first outer exhaust pipe (21) is provided coaxially with the connection exhaust pipe (140). A distal end portion (right end portion in the figure) of the connection exhaust pipe (140) is inserted into a base end portion (left end portion in FIG. 14) of the first outer exhaust pipe (21).

  The first inner exhaust pipe (22) has an outer diameter smaller than the inner diameter of the first outer exhaust pipe (21), and the inner diameter is smaller than the inner diameter of the connection exhaust pipe (140). The outer diameter of the first inner exhaust pipe (22) is equal to the inner diameter of the connection exhaust pipe (140). The length of the first inner exhaust pipe (22) is shorter than the length of the first outer exhaust pipe (21).

  The first inner exhaust pipe (22) is provided coaxially with the first outer exhaust pipe (21). In the axial direction of the first outer exhaust pipe (21), the tip of the first inner exhaust pipe (22) (the right end in FIG. 14) is located at the tip of the first outer exhaust pipe (21) (the right end in the figure). It matches the position. Further, the base end (left end in the figure) of the first inner exhaust pipe (22) and the tip end (right end in the figure) of the connection exhaust pipe (140) are separated by a predetermined distance.

  A cylindrical first cylindrical gap (23) is formed between the outer peripheral surface of the first inner exhaust pipe (22) and the inner peripheral surface of the first outer exhaust pipe (21). The width of the first cylindrical gap (23) (that is, the distance between the outer peripheral surface of the first inner exhaust pipe (22) and the inner peripheral surface of the first outer exhaust pipe (21)) is constant over its entire length. At the same time, it is constant over the entire circumference of the first inner exhaust pipe (22) and the first outer exhaust pipe (21).

  The first cylindrical gap (23) extends from the distal end side (right end side in FIG. 14) of the first outer exhaust pipe (21) to the base end portion (left end in the figure) of the second outer exhaust pipe (41) described later. Part) is inserted. In the back pressure regulator (15) of the present embodiment, the portion of the second outer exhaust pipe (41) inserted into the first cylindrical gap (23) constitutes the first spacer member (30). . The first spacer member (30) has an inner diameter equal to the outer diameter of the first inner exhaust pipe (22), and an outer diameter equal to the inner diameter of the first outer exhaust pipe (21). That is, the entire first spacer member (30) is a circular pipe portion (31).

  As in the first embodiment, a plurality of first communication openings (24), which are circular through holes, are formed near the tip of the first outer exhaust pipe (21). The plurality of first communication openings (24) are arranged in a line at equal intervals in the circumferential direction of the first outer exhaust pipe (21). The first communication opening (24) opens in a portion of the first outer exhaust pipe (21) that overlaps the first inner exhaust pipe (22), and the first cylindrical gap (23) is opened to the first outer exhaust. Communicate with the outside of the tube (21).

  As in the first embodiment, the second exhaust pipe unit (40) includes the second outer exhaust pipe (41), the second inner exhaust pipe (42), and the second spacer member (50) one by one. I have. However, in the back pressure regulator (15) of the present embodiment, the second spacer member (50) is formed integrally with a third outer exhaust pipe (61) described later.

  The inner diameter of the second outer exhaust pipe (41) is equal to the outer diameter of the first inner exhaust pipe (22), and the outer diameter is equal to the inner diameter of the first outer exhaust pipe (21). The second outer exhaust pipe (41) is provided coaxially with the first inner exhaust pipe (22). The distal end portion (the right end portion in the figure) of the first inner exhaust pipe (22) is inserted into the base end portion (the left end portion in FIG. 14) of the second outer exhaust pipe (41). As described above, the base end portion of the second outer exhaust pipe (41) constitutes the first spacer member (30) inserted into the first cylindrical gap (23).

  The outer diameter of the second inner exhaust pipe (42) is smaller than the inner diameter of the second outer exhaust pipe (41), and the inner diameter thereof is smaller than the inner diameter of the first inner exhaust pipe (22). The outer diameter of the second inner exhaust pipe (42) is equal to the inner diameter of the first inner exhaust pipe (22). The length of the second inner exhaust pipe (42) is shorter than the length of the second outer exhaust pipe (41).

  The second inner exhaust pipe (42) is provided coaxially with the second outer exhaust pipe (41). In the axial direction of the second outer exhaust pipe (41), the position of the tip of the second inner exhaust pipe (42) (the right end in FIG. 14) is the position of the tip of the second outer exhaust pipe (41) (the right end in the figure). It matches the position. Further, the base end (left end in the figure) of the second inner exhaust pipe (42) and the tip end (right end in the figure) of the first inner exhaust pipe (22) are separated by a predetermined distance.

  A cylindrical second cylindrical gap (43) is formed between the outer peripheral surface of the second inner exhaust pipe (42) and the inner peripheral surface of the second outer exhaust pipe (41). The width of the second cylindrical gap (43) (that is, the distance between the outer peripheral surface of the second inner exhaust pipe (42) and the inner peripheral surface of the second outer exhaust pipe (41)) is constant over its entire length. At the same time, it is constant over the entire circumference of the second inner exhaust pipe (42) and the second outer exhaust pipe (41).

  The second cylindrical gap (43) has a base end (left end in the figure) of a third outer exhaust pipe (61), which will be described later, from the distal end side (right end side in FIG. 14) of the second outer exhaust pipe (41). Part) is inserted. In the back pressure regulator (15) of the present embodiment, the portion of the third outer exhaust pipe (61) inserted into the second cylindrical gap (43) constitutes the second spacer member (50). . The inner diameter of the second spacer member (50) is equal to the outer diameter of the second inner exhaust pipe (42), and the outer diameter is equal to the inner diameter of the second outer exhaust pipe (41). That is, the entire second spacer member (50) is a circular pipe portion (51).

  As in the first embodiment, a plurality of second communication openings (44), which are circular through holes, are formed in a portion near the tip of the second outer exhaust pipe (41). The plurality of second communication openings (44) are arranged in a line at equal intervals in the circumferential direction of the second outer exhaust pipe (41). The second communication opening (44) opens in a portion of the second outer exhaust pipe (41) that overlaps the second inner exhaust pipe (42), and the second cylindrical gap (43) is exhausted to the second outer exhaust. Communicate with the outside of the tube (41).

  As in the first embodiment, the third exhaust pipe unit (60) includes the third outer exhaust pipe (61), the third inner exhaust pipe (62), and the third spacer member (70) one by one. I have. However, in the back pressure regulator (15) of the present embodiment, the third spacer member (70) is formed integrally with a fourth outer exhaust pipe (81) described later.

  The inner diameter of the third outer exhaust pipe (61) is equal to the outer diameter of the second inner exhaust pipe (42), and the outer diameter thereof is equal to the inner diameter of the second outer exhaust pipe (41). The third outer exhaust pipe (61) is provided coaxially with the second inner exhaust pipe (42). A distal end portion (right end portion in the figure) of the second inner exhaust pipe (42) is inserted into a base end portion (left end portion in FIG. 14) of the third outer exhaust pipe (61). As described above, the base end portion of the third outer exhaust pipe (61) constitutes the second spacer member (50) inserted into the second cylindrical gap (43).

  The outer diameter of the third inner exhaust pipe (62) is smaller than the inner diameter of the third outer exhaust pipe (61), and the inner diameter is smaller than the inner diameter of the second inner exhaust pipe (42). The outer diameter of the third inner exhaust pipe (62) is equal to the inner diameter of the second inner exhaust pipe (42). The length of the third inner exhaust pipe (62) is shorter than the length of the third outer exhaust pipe (61).

  The third inner exhaust pipe (62) is provided coaxially with the third outer exhaust pipe (61). In the axial direction of the third outer exhaust pipe (61), the tip of the third inner exhaust pipe (62) (the right end in FIG. 14) is positioned at the tip of the third outer exhaust pipe (61) (the right end in the figure). It matches the position. Further, the base end (left end in the figure) of the third inner exhaust pipe (62) and the tip end (right end in the figure) of the second inner exhaust pipe (42) are separated by a predetermined distance.

  A cylindrical third cylindrical gap (63) is formed between the outer peripheral surface of the third inner exhaust pipe (62) and the inner peripheral surface of the third outer exhaust pipe (61). The width of the third cylindrical gap (63) (that is, the distance between the outer peripheral surface of the third inner exhaust pipe (62) and the inner peripheral surface of the third outer exhaust pipe (61)) is constant over its entire length. At the same time, it is constant over the entire circumference of the third inner exhaust pipe (62) and the third outer exhaust pipe (61).

  The third cylindrical gap (63) has a base end (left end in the figure) of a fourth outer exhaust pipe (81) to be described later from the distal end side (right end side in FIG. 14) of the third outer exhaust pipe (61). Part) is inserted. In the back pressure regulator (15) of the present embodiment, the portion of the fourth outer exhaust pipe (81) inserted into the third cylindrical gap (63) constitutes the third spacer member (70). . The third spacer member (70) has an inner diameter equal to the outer diameter of the third inner exhaust pipe (62), and an outer diameter equal to the inner diameter of the third outer exhaust pipe (61). That is, the entire third spacer member (70) is a circular pipe portion (71).

  As in the first embodiment, a plurality of third communication openings (64), which are circular through holes, are formed in the portion near the tip of the third outer exhaust pipe (61). The plurality of third communication openings (64) are arranged in a line at equal intervals in the circumferential direction of the third outer exhaust pipe (61). The third communication opening (64) opens in a portion of the third outer exhaust pipe (61) that overlaps the third inner exhaust pipe (62), and the third cylindrical gap (63) is exhausted to the third outer exhaust. Communicate with the outside of the tube (61).

  The fourth exhaust pipe unit (80) includes a fourth outer exhaust pipe (81), a fourth inner exhaust pipe (82), and a fourth spacer member (90) one by one. In the back pressure regulator (15) of the present embodiment, the fourth spacer member (90) is formed integrally with a fifth outer exhaust pipe (101) described later.

  The inner diameter of the fourth outer exhaust pipe (81) is equal to the outer diameter of the third inner exhaust pipe (62), and the outer diameter is equal to the inner diameter of the third outer exhaust pipe (61). The fourth outer exhaust pipe (81) is provided coaxially with the third inner exhaust pipe (62). The distal end portion (the right end portion in the figure) of the third inner exhaust pipe (62) is inserted into the base end portion (the left end portion in FIG. 14) of the fourth outer exhaust pipe (81). As described above, the base end portion of the fourth outer exhaust pipe (81) constitutes the third spacer member (70) to be inserted into the third cylindrical gap (63).

  The outer diameter of the fourth inner exhaust pipe (82) is smaller than the inner diameter of the fourth outer exhaust pipe (81), and the inner diameter is smaller than the inner diameter of the third inner exhaust pipe (62). The outer diameter of the fourth inner exhaust pipe (82) is equal to the inner diameter of the third inner exhaust pipe (62). The length of the fourth inner exhaust pipe (82) is shorter than the length of the fourth outer exhaust pipe (81).

  The fourth inner exhaust pipe (82) is provided coaxially with the fourth outer exhaust pipe (81). In the axial direction of the fourth outer exhaust pipe (81), the tip end (right end in FIG. 14) of the fourth inner exhaust pipe (82) is located at the tip end (right end in FIG. 14) of the fourth outer exhaust pipe (81). It matches the position. Further, the base end (left end in the figure) of the fourth inner exhaust pipe (82) and the tip end (right end in the figure) of the third inner exhaust pipe (62) are separated by a predetermined distance.

  A cylindrical fourth cylindrical gap (83) is formed between the outer peripheral surface of the fourth inner exhaust pipe (82) and the inner peripheral surface of the fourth outer exhaust pipe (81). The width of the fourth cylindrical gap (83) (that is, the distance between the outer peripheral surface of the fourth inner exhaust pipe (82) and the inner peripheral surface of the fourth outer exhaust pipe (81)) is constant over its entire length. At the same time, it is constant over the entire circumference of the fourth inner exhaust pipe (82) and the fourth outer exhaust pipe (81).

  The fourth cylindrical gap (83) extends from the distal end side (right end side in FIG. 14) of the fourth outer exhaust pipe (81) to the base end portion (left end in the figure) of the fifth outer exhaust pipe (101) described later. Part) is inserted. In the back pressure regulator (15) of the present embodiment, the portion of the fifth outer exhaust pipe (101) inserted into the fourth cylindrical gap (83) constitutes the fourth spacer member (90). . The fourth spacer member (90) has an inner diameter equal to the outer diameter of the fourth inner exhaust pipe (82) and an outer diameter equal to the inner diameter of the fourth outer exhaust pipe (81). That is, the entire fourth spacer member (90) is a circular pipe portion (91).

  A plurality of fourth communication openings (84), which are circular through holes, are formed in a portion near the tip of the fourth outer exhaust pipe (81). The plurality of fourth communication openings (84) are arranged in a line at equal intervals in the circumferential direction of the fourth outer exhaust pipe (81). The fourth communication opening (84) opens in a portion of the fourth outer exhaust pipe (81) that overlaps the fourth inner exhaust pipe (82), and the fourth cylindrical gap (83) passes through the fourth outer exhaust. Communicate with the outside of the tube (81).

  The fifth exhaust pipe unit (100) includes a fifth outer exhaust pipe (101), a fifth inner exhaust pipe (102), and a fifth spacer member (110). In the back pressure regulator (15) of the present embodiment, the fifth spacer member (110) is formed integrally with a sixth outer exhaust pipe (121) described later.

  The inner diameter of the fifth outer exhaust pipe (101) is equal to the outer diameter of the fourth inner exhaust pipe (82), and the outer diameter is equal to the inner diameter of the fourth outer exhaust pipe (81). The fifth outer exhaust pipe (101) is provided coaxially with the fourth inner exhaust pipe (82). A distal end portion (right end portion in the figure) of the fourth inner exhaust pipe (82) is inserted into a base end portion (left end portion in FIG. 14) of the fifth outer exhaust pipe (101). As described above, the base end portion of the fifth outer exhaust pipe (101) constitutes the fourth spacer member (90) inserted into the fourth cylindrical gap (83).

  The outer diameter of the fifth inner exhaust pipe (102) is smaller than the inner diameter of the fifth outer exhaust pipe (101), and the inner diameter thereof is smaller than the inner diameter of the fourth inner exhaust pipe (82). The outer diameter of the fifth inner exhaust pipe (102) is equal to the inner diameter of the fourth inner exhaust pipe (82). The length of the fifth inner exhaust pipe (102) is shorter than the length of the fifth outer exhaust pipe (101).

  The fifth inner exhaust pipe (102) is provided coaxially with the fifth outer exhaust pipe (101). In the axial direction of the fifth outer exhaust pipe (101), the position of the tip of the fifth inner exhaust pipe (102) (the right end in FIG. 14) is the position of the tip of the fifth outer exhaust pipe (101) (the right end in the figure). It matches the position. Further, the base end (left end in the figure) of the fifth inner exhaust pipe (102) and the tip end (right end in the figure) of the fourth inner exhaust pipe (82) are separated by a predetermined distance.

  A cylindrical fifth cylindrical gap (103) is formed between the outer peripheral surface of the fifth inner exhaust pipe (102) and the inner peripheral surface of the fifth outer exhaust pipe (101). The width of the fifth cylindrical gap (103) (that is, the distance between the outer peripheral surface of the fifth inner exhaust pipe (102) and the inner peripheral surface of the fifth outer exhaust pipe (101)) is constant over its entire length. At the same time, it is constant over the entire circumference of the fifth inner exhaust pipe (102) and the fifth outer exhaust pipe (101).

  The fifth cylindrical gap (103) extends from the distal end side (right end side in FIG. 14) of the fifth outer exhaust pipe (101) to the base end portion (left end in the figure) of the sixth outer exhaust pipe (121) described later. Part) is inserted. In the back pressure regulator (15) of the present embodiment, the portion of the sixth outer exhaust pipe (121) inserted into the fifth cylindrical gap (103) constitutes the fifth spacer member (110). . The fifth spacer member (110) has an inner diameter equal to the outer diameter of the fifth inner exhaust pipe (102), and an outer diameter equal to the inner diameter of the fifth outer exhaust pipe (101). That is, the fifth spacer member (110) as a whole is a circular pipe portion (111).

  A plurality of fifth communication openings (104), which are circular through holes, are formed in a portion near the tip of the fifth outer exhaust pipe (101). The plurality of fifth communication openings (104) are arranged in a line at equal intervals in the circumferential direction of the fifth outer exhaust pipe (101). The fifth communication opening (104) opens in a portion of the fifth outer exhaust pipe (101) that overlaps the fifth inner exhaust pipe (102), and the fifth cylindrical gap (103) is exhausted to the fifth outer exhaust. Communicate with the outside of the tube (101).

  The sixth exhaust pipe unit (120) includes a sixth outer exhaust pipe (121), a sixth inner exhaust pipe (122), and a sixth spacer member (130).

  The inner diameter of the sixth outer exhaust pipe (121) is equal to the outer diameter of the fifth inner exhaust pipe (102), and the outer diameter thereof is equal to the inner diameter of the fifth outer exhaust pipe (101). The sixth outer exhaust pipe (121) is provided coaxially with the fifth inner exhaust pipe (102). The distal end portion (the right end portion in the figure) of the fifth inner exhaust pipe (102) is inserted into the base end portion (the left end portion in FIG. 14) of the sixth outer exhaust pipe (121). As described above, the base end portion of the sixth outer exhaust pipe (121) constitutes the fifth spacer member (110) inserted into the fifth cylindrical gap (103).

  The outer diameter of the sixth inner exhaust pipe (122) is smaller than the inner diameter of the sixth outer exhaust pipe (121), and the inner diameter is smaller than the inner diameter of the fifth inner exhaust pipe (102). The outer diameter of the sixth inner exhaust pipe (122) is equal to the inner diameter of the fifth inner exhaust pipe (102). The length of the sixth inner exhaust pipe (122) is shorter than the length of the sixth outer exhaust pipe (121).

  The sixth inner exhaust pipe (122) is provided coaxially with the sixth outer exhaust pipe (121). In the axial direction of the sixth outer exhaust pipe (121), the position of the tip (the right end in FIG. 14) of the sixth inner exhaust pipe (122) is the position of the tip (the right end in the figure) of the sixth outer exhaust pipe (121). It matches the position. Further, the base end (left end in the figure) of the sixth inner exhaust pipe (122) and the tip end (right end in the figure) of the fifth inner exhaust pipe (102) are separated by a predetermined distance.

  A cylindrical sixth cylindrical gap (123) is formed between the outer peripheral surface of the sixth inner exhaust pipe (122) and the inner peripheral surface of the sixth outer exhaust pipe (121). The width of the sixth cylindrical gap (123) (that is, the distance between the outer peripheral surface of the sixth inner exhaust pipe (122) and the inner peripheral surface of the sixth outer exhaust pipe (121)) is constant over its entire length. At the same time, it is constant over the entire circumference of the sixth inner exhaust pipe (122) and the sixth outer exhaust pipe (121).

  A sixth spacer member (130) is inserted into the sixth cylindrical gap (123) from the distal end side (the right end side in FIG. 14) of the sixth outer exhaust pipe (121). The sixth spacer member (130) is a relatively short tubular member having an inner diameter equal to the outer diameter of the sixth inner exhaust pipe (122), and the outer diameter of the sixth outer exhaust pipe (121). It is equal to the inner diameter. That is, the sixth spacer member (130) as a whole is a circular pipe portion (131).

  A plurality of sixth communication openings (124), which are circular through holes, are formed in a portion near the tip of the sixth outer exhaust pipe (121). The plurality of sixth communication openings (124) are arranged in a line at equal intervals in the circumferential direction of the sixth outer exhaust pipe (121). The sixth communication opening (124) opens in a portion of the sixth outer exhaust pipe (121) that overlaps the sixth inner exhaust pipe (122), and the sixth cylindrical gap (123) passes through the sixth outer exhaust pipe. Communicate with the outside of the tube (121).

-Back pressure adjustment action of back pressure regulator-
The back pressure regulating action of the back pressure regulator (15) of the present embodiment is the same as that of the first embodiment. However, this exhaust pressure regulator (15) is provided with six exhaust pipe units (20, 40, 60, 80, 100, 120). Therefore, in the back pressure regulator (15), the area of the portion from which the exhaust gas flows out changes in seven stages according to the flow rate of the exhaust gas.

  Specifically, in the back pressure regulator (15) of the present embodiment, the exhaust gas is released only from the first communication opening (24) when the flow rate of the exhaust gas is the smallest. In this state, air is sucked into the second to sixth communication openings (44, 64, 84, 104, 124) and the tip of the sixth inner exhaust pipe (122).

  When the flow rate of the exhaust gas increases from this state, exhaust gas begins to be released not only from the first communication opening (24) but also from the second communication opening (44). In this state, air is sucked into the tips of the third to sixth communication openings (64, 84, 104, 124) and the sixth inner exhaust pipe (122).

  When the flow rate of the exhaust gas further increases from this state, the exhaust gas starts to be released not only from the first communication opening (24) and the second communication opening (44) but also from the third communication opening (64). In this state, air is sucked into the tips of the fourth to sixth communication openings (84, 104, 124) and the sixth inner exhaust pipe (122).

  When the flow rate of the exhaust gas further increases from this state, the exhaust gas starts to be released not only from the first to third communication openings (24, 44, 64) but also from the fourth communication opening (84). In this state, air is sucked into the tips of the fifth to sixth communication openings (104, 124) and the sixth inner exhaust pipe (122).

  When the flow rate of the exhaust gas further increases from this state, the exhaust gas begins to be released not only from the first to fourth communication openings (24, 44, 64, 84) but also from the fifth communication opening (104). . In this state, air is sucked into the tips of the sixth communication opening (124) and the sixth inner exhaust pipe (122).

  When the flow rate of the exhaust gas further increases from this state, exhaust gas begins to be released not only from the first to fifth communication openings (24, 44, 64, 84, 104) but also from the sixth communication opening (124). . In this state, air is sucked into the tip of the sixth inner exhaust pipe (122).

  If the flow rate of the exhaust gas further increases from this state, the exhaust gas not only from the first to sixth communication openings (24, 44, 64, 84, 104, 124) but also from the tip of the sixth inner exhaust pipe (122). Begins to be released. That is, in this state, exhaust gas is discharged from all seven locations of the first to sixth communication openings (24, 44, 64, 84, 104, 124) and the tip of the sixth inner exhaust pipe (122).

-Effect of Embodiment 3-
In the back pressure regulator (15) of the present embodiment, the spacer member (30, 50, 70, 90, 110) of the exhaust pipe unit (20, 40, 60, 80, 100) disposed on the upstream side of the exhaust gas flow is It is integrated with the outer exhaust pipe (41, 61, 81, 101, 121) of the exhaust pipe unit (40, 60, 80, 100, 120) arranged on the downstream side. That is, in this back pressure regulator (15), the outer exhaust pipe (41, 61, 81, 101, 121) of the exhaust pipe unit (40, 60, 80, 100, 120) arranged on the downstream side of the exhaust gas flow is located on the upstream side. It also serves as the spacer member (30, 50, 70, 90, 110) of the arranged exhaust pipe unit (20, 40, 60, 80, 100). Therefore, according to this embodiment, the number of parts constituting the back pressure regulator (15) can be reduced, and as a result, the structure of the exhaust device (10) can be simplified, and the exhaust device Man-hours required for assembly in (10) can be reduced.

<< Other Embodiments >>
-First modification-
In the exhaust device (10) of the first and second embodiments, three exhaust pipe units (20, 40, 60) are provided in the back pressure regulator (15). In the exhaust device (10) of the third embodiment, the back pressure regulator (15) is provided with six exhaust pipe units (20, 40, 60, 80, 100, 120). The number of exhaust pipe units (20, 40,...) In the back pressure regulator (15) of these embodiments is merely an example. The number of exhaust pipe units (20, 40, 60) provided in the back pressure regulator (15) is appropriately determined according to the use of the engine and the like.

  For example, as shown in FIG. 15, the back pressure regulator (15) may be provided with only one exhaust pipe unit (20). In this case, the cross-sectional area of the passage that passes when the exhaust gas is discharged from the back pressure regulator (15) into the atmosphere changes in two stages according to the flow rate of the exhaust gas. If the engine to which the back pressure regulator (15) is connected has a small fluctuation range of the rotational speed during operation, the back pressure regulator (15) having only one exhaust pipe unit (20) can also be used. A sufficient effect can be obtained.

  FIG. 15 shows the exhaust device (10) of Embodiment 2 in which only one exhaust pipe unit (20) is provided in the back pressure regulator (15). In the back pressure regulator (15), when the flow rate of the exhaust gas is small, the exhaust gas is discharged only from the communication opening (24), and the air is sucked into the tip of the inner exhaust pipe (22). When the flow rate of the exhaust gas increases from this state, the exhaust gas starts to be released not only from the communication opening (24) but also from the tip of the inner exhaust pipe (22).

-Second modification-
In each of the above embodiments, the silencer (211) and the back pressure regulator (15) constitute the exhaust device (10). However, the back pressure regulator (15) alone constitutes the exhaust device (10). May be.

  As described above, the present invention is useful for an exhaust device that can adjust the flow resistance of exhaust gas without using mechanical means such as a valve.

Claims (11)

An outer exhaust pipe (21, 41, 61) that is formed in a circular tube and into which the exhaust gas of the internal combustion engine flows from the base end side;
An inner exhaust pipe (22, 42, 62) formed into a circular tube having an outer diameter smaller than the inner diameter of the outer exhaust pipe and inserted into the tip of the outer exhaust pipe (21, 41, 61);
In order to make the interval between the inner peripheral surface of the outer exhaust pipe (21, 41, 61) and the outer peripheral surface of the inner exhaust pipe (22, 42, 62) constant over the entire circumference, the outer exhaust pipe (21, 41, 61) and the spacing member (30, 50, 70) provided between the inner exhaust pipe (22, 42, 62),
A cylindrical gap (23, 43, 63) formed between the inner peripheral surface of the outer exhaust pipe (21, 41, 61) and the outer peripheral surface of the inner exhaust pipe (22, 42, 62) is used as the outer exhaust. An exhaust system comprising a communication opening (24, 44, 64) for communicating with the outside of the pipe (21, 41, 61). In claim 1,
The spacing member (30, 50, 70) is inserted into the cylindrical gap (23, 43, 63), and the inner peripheral surface of the outer exhaust pipe (21, 41, 61) and the inner exhaust pipe ( Exhaust device characterized by being in contact with both outer peripheral surfaces of 22,42,62). In claim 2,
The spacing member (30, 50, 70) is inserted into the cylindrical gap (23, 43, 63) from the front end side of the outer exhaust pipe (21, 41, 61). Exhaust system. In claim 3,
The spacing member (30, 50, 70) has an outer diameter equal to the inner diameter of the outer exhaust pipe (21, 41, 61) and an inner diameter equal to the outer diameter of the inner exhaust pipe (22, 42, 62). While provided with a circular pipe portion (31, 51, 71) formed into an equal circular tube and inserted into the cylindrical gap (23, 43, 63),
In the outer exhaust pipe (21, 41, 61), the cylindrical gap (23, 42, 62) overlaps with the inner exhaust pipe (22, 42, 62) inserted into the outer exhaust pipe (21, 41, 61). 43, 63) is formed, and a through hole is formed.
The exhaust apparatus, wherein the through hole constitutes the communication opening (24, 44, 64). In claim 4,
The spacing member (30, 50, 70) has an annular protrusion (32, 52, 72) formed in an annular shape whose outer diameter is larger than the inner diameter of the outer exhaust pipe (21, 41, 61). , Continuously formed at the tip of the circular pipe part (31, 51, 71),
The exhaust device characterized in that the annular projection (32, 52, 72) is in contact with the front end surface of the outer exhaust pipe (21, 41, 61). In claim 3,
The spacing member (30, 50, 70) has an outer diameter equal to the inner diameter of the outer exhaust pipe (21, 41, 61) and an inner diameter equal to the outer diameter of the inner exhaust pipe (22, 42, 62). While formed into equal circular tube,
The spacing member (30, 50, 70) has a notch extending in the axial direction of the spacing member (30, 50, 70) from the base end of the spacing member (30, 50, 70). (33,53,73) is formed,
The spacing member (30, 50, 70) is arranged so that only a part of the notch (33, 53, 73) is covered with the outer exhaust pipe (21, 41, 61). (30, 50, 70) is inserted into the cylindrical gap (23, 43, 63) from the base end side,
The portion of the notch (33, 53, 73) that is not covered by the outer exhaust pipe (21, 41, 61) constitutes the communication opening (24, 44, 64). Exhaust system. In claim 1, 2, 3, 4, 5 or 6,
An exhaust system comprising a tubular member (18) formed in a tubular shape and having an inner surface facing the outer peripheral surface of the outer exhaust pipe (21, 41, 61) at a distance. In claim 7,
Blocking that closes between the tubular member (18) and the outer exhaust pipe (21, 41) closer to the base end of the outer exhaust pipe (21, 41) than the communication opening (24, 44) An exhaust device comprising a member for use (218). In claim 1, 2, 3, 4, 5 or 6,
Each is composed of one outer exhaust pipe (21, 41, 61), the inner exhaust pipe (22, 42, 62) and the spacing member (30, 50, 70), and A plurality of exhaust pipe units (20, 40, 60) having the communication openings (24, 44, 64);
The plurality of exhaust pipe units (20, 40, 60) are arranged in a row so that the outer exhaust pipes (21, 41, 61) and the inner exhaust pipes (22, 42, 62) are coaxially positioned. While
In the two adjacent exhaust pipe units (20, 40),
The inner diameter of the inner exhaust pipe (42) constituting the downstream exhaust pipe unit (40) is smaller than the inner diameter of the inner exhaust pipe (22) of the upstream exhaust pipe unit (20),
The inner diameter of the outer exhaust pipe (41) constituting the downstream exhaust pipe unit (40) is equal to the outer diameter of the inner exhaust pipe (22) of the upstream exhaust pipe unit (20),
The distal end of the inner exhaust pipe (22) constituting the upstream exhaust pipe unit (20) is inserted into the base end of the outer exhaust pipe (41) constituting the downstream exhaust pipe unit (40),
A gap is formed between the proximal end of the inner exhaust pipe (42) of the downstream exhaust pipe unit (40) and the distal end of the inner exhaust pipe (22) of the upstream exhaust pipe unit (20). Exhaust device characterized. In claim 4 or 6,
Each is composed of one outer exhaust pipe (21, 41, 61), the inner exhaust pipe (22, 42, 62) and the spacing member (30, 50, 70), and A plurality of exhaust pipe units (20, 40, 60) having the communication openings (24, 44, 64);
The plurality of exhaust pipe units (20, 40, 60) are arranged in a row so that the outer exhaust pipes (21, 41, 61) and the inner exhaust pipes (22, 42, 62) are coaxially positioned. While
In the two adjacent exhaust pipe units (20, 40),
The inner diameter of the inner exhaust pipe (42) constituting the downstream exhaust pipe unit (40) is smaller than the inner diameter of the inner exhaust pipe (22) constituting the upstream exhaust pipe unit (20),
The inner side of the outer exhaust pipe (41) constituting the downstream side exhaust pipe unit (40) is smaller than the inner diameter of the outer side exhaust pipe (21) of the upstream side exhaust pipe unit (20) and the upstream side exhaust pipe unit. Larger than the inner diameter of the inner exhaust pipe (22) of (20),
The distal end of the inner exhaust pipe (22) constituting the upstream exhaust pipe unit (20) is inserted into the base end of the outer exhaust pipe (41) constituting the downstream exhaust pipe unit (40),
A cylindrical gap (43) formed between the outer exhaust pipe (41) and the inner exhaust pipe (42) constituting the downstream exhaust pipe unit (40) constitutes the upstream exhaust pipe unit (20). Communicating with the space inside the inner exhaust pipe (22)
An exhaust system characterized in that an outer exhaust pipe (41) of a downstream exhaust pipe unit (40) and an interval holding member (30) of an upstream exhaust pipe unit (20) are integrally formed. In claim 1, 2, 3, 4, 5 or 6,
Each is composed of one outer exhaust pipe (21, 41, 61), the inner exhaust pipe (22, 42, 62) and the spacing member (30, 50, 70), and A plurality of exhaust pipe units (20, 40, 60) having the communication openings (24, 44, 64);
The plurality of exhaust pipe units (20, 40, 60) are arranged in a row so that the outer exhaust pipes (21, 41, 61) and the inner exhaust pipes (22, 42, 62) are coaxially positioned. While
An exhaust system comprising a tubular member (18) formed in a tubular shape and having an inner surface facing the outer peripheral surfaces of all the outer exhaust pipes (21, 41, 61) at a distance.

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